/**
 * css-learning.css - 当发网 CSS 学习教程样式表
 * 版本：4.0.0
 * 描述：提供 CSS 学习教程的整体视觉风格、布局及交互演示样式。
 */

/* ===== 1. CSS 自定义属性（变量） ===== */
:root {
  --primary-color: #82255e;
  --primary-dark: #6a1e4c;
  --secondary-color: #b83b6a;
  --accent-color: #d1c39d;
  --dark-color: #2a101b;
  --light-color: #d9d0ca;
  --white: #ffffff;
  --gray-light: #f5f5f5;
  --gray-medium: #e0e0e0;

  --font-family:
    "微软雅黑", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;

  --border-radius: 10px;

  --transition: all 0.3s ease;

  --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-hover: 0 8px 15px rgba(0, 0, 0, 0.15);

  --demo-primary: #82255e;
  --demo-spacing: 16px;
  --demo-radius: 5px;
  --demo-shadow: 5px;
  --demo-font-size: 16px;

  --pattern-svg: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" width="20" height="20"><rect width="10" height="10" fill="%2382255E"/><rect x="10" y="10" width="10" height="10" fill="%23B83B6A"/></svg>');
}

/* ===== 2. 重置样式（Reset & Normalize） ===== */
body,
h1,
h2,
h3,
h4,
p,
ul,
li,
article,
header,
footer,
main,
nav,
div {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* ===== 3. 基础样式（Base） ===== */
html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  line-height: 1.6;
  color: #333;
  background-color: var(--gray-light);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.container {
  width: 100%;
  margin: 0 auto;
  padding: 0 15px;
}

/* ===== 4. 布局组件 ===== */

/* ---------- 头部（Header） ---------- */
header {
  background-color: var(--primary-color);
  color: var(--accent-color);
  text-align: center;
  padding: 1.5rem 1rem;
  border-radius: var(--border-radius) var(--border-radius) 0 0;
  position: relative;
  overflow: hidden;
  box-shadow: var(--shadow);
}

.header-content {
  position: relative;
  z-index: 1;
}

header h1 {
  font-size: 1.8rem;
  font-weight: 900;
  margin: 0 0 0.5rem 0;
  text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

header p {
  font-size: 1rem;
  margin-bottom: 1rem;
  opacity: 0.9;
}

.header-links,
.footer-nav-links {
  display: flex;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.header-links a,
.footer-nav-links a {
  color: var(--accent-color);
  text-decoration: none;
  padding: 0.5rem 1rem;
  border: 1px solid var(--accent-color);
  border-radius: var(--border-radius);
  transition: var(--transition);
  font-size: 0.9rem;
}

.header-links a:hover,
.footer-nav-links a:hover {
  background-color: var(--accent-color);
  color: var(--primary-color);
}

/* ---------- 主导航（Navigation） ---------- */
.main-nav {
  background-color: var(--dark-color);
  position: relative;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

.nav-menu {
  display: flex;
  list-style: none;
  flex-wrap: wrap;
  justify-content: center;
  padding: 0;
  margin: 0;
  transition: var(--transition);
}

.nav-menu li {
  margin: 0;
}

.nav-menu a {
  display: block;
  color: var(--light-color);
  text-decoration: none;
  padding: 0.8rem 1.2rem;
  transition: var(--transition);
  font-weight: 500;
  font-size: 0.95rem;
  text-align: center;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.nav-menu a:hover,
.nav-menu a.active {
  background-color: var(--primary-color);
  color: var(--accent-color);
}

.hamburger {
  display: none;
  flex-direction: column;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  margin-left: auto;
  position: absolute;
  right: 1rem;
  top: 50%;
  transform: translateY(-50%);
  z-index: 100;
  transition: var(--transition);
}

.hamburger span {
  display: block;
  width: 25px;
  height: 3px;
  background-color: var(--accent-color);
  margin: 3px 0;
  transition: var(--transition);
  border-radius: 2px;
}

/* ---------- 主内容区（Main） ---------- */
main {
  background-color: var(--secondary-color);
  padding: 1.5rem 1rem;
  flex-grow: 1;
}

/* ---------- 英雄区域（Hero Section） ---------- */
.hero-section {
  display: flex;
  flex-direction: column;
  gap: 2rem;
  margin-bottom: 3rem;
}

.hero-content {
  background-color: var(--accent-color);
  padding: 2rem;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
  text-align: center;
}

.hero-content h2 {
  color: var(--primary-color);
  margin-bottom: 1rem;
  font-size: 1.8rem;
}

.hero-content p {
  color: var(--dark-color);
  font-size: 1.1rem;
  margin-bottom: 1.5rem;
  line-height: 1.7;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 2rem;
  flex-wrap: wrap;
}

.stat {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.stat-number {
  font-size: 2rem;
  font-weight: bold;
  color: var(--primary-color);
}

.stat-label {
  font-size: 0.9rem;
  color: var(--dark-color);
}

.hero-visual {
  display: flex;
  justify-content: center;
}

.code-preview {
  background-color: var(--dark-color);
  border-radius: var(--border-radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  width: 100%;
  max-width: 500px;
}

.code-title {
  color: var(--light-color);
  font-size: 0.9rem;
  font-weight: 500;
}

.code-content {
  padding: 1rem;
}

.code-content pre {
  margin: 0;
  overflow-x: auto;
}

.code-content code {
  display: block;
  color: var(--light-color);
  font-family: "Courier New", Courier, monospace;
  font-size: 0.9rem;
  line-height: 1.5;
  white-space: pre;
}

/* ---------- 学习路径（Learning Path） ---------- */
.learning-path {
  margin-bottom: 3rem;
}

.learning-path h2 {
  color: var(--accent-color);
  text-align: center;
  margin-bottom: 2rem;
  font-size: 1.8rem;
}

.path-steps {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.path-step {
  background-color: var(--accent-color);
  padding: 1.5rem;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  transition: var(--transition);
}

.path-step:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-hover);
}

.step-number {
  width: 40px;
  height: 40px;
  background-color: var(--primary-color);
  color: var(--accent-color);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
  margin-bottom: 1rem;
}

.path-step h3 {
  color: var(--primary-color);
  margin-bottom: 0.5rem;
  font-size: 1.3rem;
}

.path-step p {
  color: var(--dark-color);
  margin-bottom: 1rem;
}

.step-link {
  display: inline-block;
  background-color: var(--primary-color);
  color: var(--accent-color);
  padding: 0.5rem 1rem;
  border-radius: var(--border-radius);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
}

.step-link:hover {
  background-color: var(--primary-dark);
}

/* ---------- 特色卡片（Featured Cards） ---------- */
.featured-cards {
  margin-bottom: 3rem;
}

.featured-cards h2 {
  color: var(--accent-color);
  text-align: center;
  margin-bottom: 2rem;
  font-size: 1.8rem;
}

.cards-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
}

.featured-card {
  background-color: var(--accent-color);
  padding: 1.5rem;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
  text-align: center;
  transition: var(--transition);
  display: flex;
  flex-direction: column;
  align-items: center;
}

.featured-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-hover);
}

.card-icon {
  width: 50px;
  height: 50px;
  background-color: var(--primary-color);
  color: var(--accent-color);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1rem;
}

.featured-card h3 {
  color: var(--primary-color);
  margin-bottom: 1rem;
  font-size: 1.3rem;
}

.featured-card p {
  color: var(--dark-color);
  margin-bottom: 1.5rem;
  flex-grow: 1;
}

.card-link {
  display: inline-block;
  background-color: var(--primary-color);
  color: var(--accent-color);
  padding: 0.5rem 1rem;
  border-radius: var(--border-radius);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
}

.card-link:hover {
  background-color: var(--primary-dark);
}

/* ---------- 快速链接（Quick Links） ---------- */
.quick-links {
  margin-bottom: 2rem;
}

.quick-links h2 {
  color: var(--accent-color);
  text-align: center;
  margin-bottom: 2rem;
  font-size: 1.8rem;
}

.links-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
}

.quick-link {
  background-color: var(--accent-color);
  padding: 1rem;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
  text-decoration: none;
  transition: var(--transition);
  display: flex;
  flex-direction: column;
}

.quick-link:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-hover);
}

.link-title {
  color: var(--primary-color);
  font-weight: bold;
  margin-bottom: 0.25rem;
}

.link-desc {
  color: var(--dark-color);
  font-size: 0.9rem;
}

/* ---------- 内容区块（Content Section） ---------- */
.content-section {
  background-color: var(--accent-color);
  padding: 1.5rem;
  border-radius: var(--border-radius);
  margin-bottom: 1.5rem;
  box-shadow: var(--shadow);
}

.content-section h2 {
  color: var(--primary-color);
  margin-bottom: 1rem;
  font-size: 1.6rem;
  border-bottom: 2px solid var(--primary-color);
  padding-bottom: 0.5rem;
}

.content-section h3 {
  color: var(--primary-dark);
  margin: 1.5rem 0 1rem 0;
  font-size: 1.3rem;
}

.content-section p {
  margin-bottom: 1rem;
  line-height: 1.7;
}

.content-section ul,
.content-section ol {
  margin: 0 0 1rem 1.5rem;
}

.content-section li {
  margin-bottom: 0.5rem;
}

/* ---------- 代码示例（Code Example） ---------- */
.code-example {
  background-color: var(--dark-color);
  color: var(--light-color);
  border-radius: var(--border-radius);
  margin: 1rem 0;
  overflow: hidden;
}

.code-header {
  background-color: #1a1a1a;
  padding: 0.75rem 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.code-content pre {
  margin: 0;
  font-family: "Courier New", Courier, monospace;
  font-size: 0.9rem;
  line-height: 1.5;
}

.code-content code {
  display: block;
  white-space: pre;
}

.line-number {
  display: inline-block;
  width: 2.5em;
  padding-right: 1em;
  margin-right: 1em;
  color: #6c757d;
  text-align: right;
  border-right: 1px solid #444;
  user-select: none;
}

.example-preview {
  background-color: var(--white);
  border: 1px solid var(--gray-medium);
  padding: 1rem;
  border-radius: var(--border-radius);
  margin: 1rem 0;
}

/* ---------- 提示框（Tip & Warning） ---------- */
.tip-box {
  background-color: #e8f4fd;
  border-left: 4px solid #2196f3;
  padding: 1rem;
  margin: 1rem 0;
  border-radius: 0 var(--border-radius) var(--border-radius) 0;
}

.warning-box {
  background-color: #ffebee;
  border-left: 4px solid #f44336;
  padding: 1rem;
  margin: 1rem 0;
  border-radius: 0 var(--border-radius) var(--border-radius) 0;
}

/* ---------- 表格（Table） ---------- */
.syntax-table,
.syntax-table table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  background-color: var(--white);
  border-radius: var(--border-radius);
  overflow: hidden;
  box-shadow: var(--shadow);
}

.syntax-table th,
.syntax-table td {
  padding: 0.75rem;
  text-align: left;
  border-bottom: 1px solid var(--gray-medium);
}

.syntax-table th {
  background-color: var(--primary-color);
  color: var(--accent-color);
  font-weight: 600;
}

.syntax-table tr:last-child td {
  border-bottom: none;
}

.syntax-table tr:hover {
  background-color: var(--gray-light);
}

/* ---------- 浏览器支持（Browser Support） ---------- */
.browser-support {
  background-color: var(--white);
  border-radius: var(--border-radius);
  padding: 1rem;
  margin: 1rem 0;
  border-left: 4px solid #4caf50;
}

.support-item {
  display: flex;
  align-items: center;
  margin-bottom: 0.5rem;
}

.support-browser {
  width: 100px;
  font-weight: bold;
}

.support-version {
  flex: 1;
}

/* ---------- 标签列表（Tag List） ---------- */
.tag-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 0.5rem;
  margin: 1rem 0;
}

.tag-item {
  background-color: var(--white);
  padding: 0.5rem;
  border-radius: 4px;
  border-left: 3px solid var(--primary-color);
  font-family: "Courier New", Courier, monospace;
  font-size: 0.9rem;
}

/* ---------- 表单（Form） ---------- */
.form-preview {
  background-color: var(--white);
  padding: 1.5rem;
  border-radius: var(--border-radius);
  border: 1px solid var(--gray-medium);
  margin: 1rem 0;
}

.form-group {
  margin-bottom: 1rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: bold;
}

.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 0.5rem;
  border: 1px solid var(--gray-medium);
  border-radius: 4px;
  font-family: inherit;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 2px rgba(130, 37, 94, 0.2);
}

.example-image {
  max-width: 100%;
  height: auto;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
}

/* ---------- 代码语法高亮（Syntax Highlighting） ---------- */
.code-content .tag {
  color: #e06c75;
}

.code-content .attr {
  color: #d19a66;
}

.code-content .value {
  color: #98c379;
}

.code-content .comment {
  color: #5c6370;
}

/* ---------- 复制按钮与折叠（Copy & Collapse） ---------- */
.copy-code-btn {
  background: var(--primary-color);
  color: white;
  border: none;
  padding: 6px 12px;
  border-radius: 4px;
  cursor: pointer;
  font-size: 0.8rem;
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  gap: 4px;
  margin-left: auto;
}

.copy-code-btn:hover {
  background: var(--primary-dark);
  transform: translateY(-1px);
}

.copy-code-btn.copied {
  background: #28a745;
}

.copy-code-btn svg {
  width: 14px;
  height: 14px;
}

.code-content.collapsed {
  max-height: 0;
  overflow: hidden;
}

.code-content {
  transition: max-height 0.3s ease-out;
}

/* ---------- 快速导航（Quick Nav） ---------- */
.quick-nav.visible {
  opacity: 1;
  transform: translateY(0);
}

.quick-nav {
  opacity: 0;
  transform: translateY(20px);
  transition: all 0.3s ease;
}

/* ---------- 表单页面特定（Form Demo） ---------- */
.form-demo-section {
  background-color: var(--white);
  padding: 1.5rem;
  border-radius: var(--border-radius);
  border: 1px solid var(--gray-medium);
  margin: 1rem 0;
}

.form-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}

.form-example {
  background-color: var(--gray-light);
  padding: 1rem;
  border-radius: var(--border-radius);
  margin-bottom: 1rem;
}

.validation-demo {
  background-color: #e8f4fd;
  border-left: 4px solid #2196f3;
  padding: 1rem;
  margin: 1rem 0;
  border-radius: 0 var(--border-radius) var(--border-radius) 0;
}

/* ---------- 参考手册页面（Reference） ---------- */
.search-box {
  margin: 20px 0;
  position: relative;
}

.search-box input {
  width: 100%;
  padding: 12px 20px;
  border: 2px solid var(--primary-color);
  border-radius: var(--border-radius);
  font-size: 1rem;
  box-sizing: border-box;
}

.search-results {
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background: white;
  border: 1px solid var(--gray-medium);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-hover);
  z-index: 15;
  max-height: 300px;
  overflow-y: auto;
  display: none;
}

.search-box {
  position: relative;
  z-index: 20;
}

.quick-nav {
  position: relative;
  z-index: 10;
  margin-top: 15px;
  opacity: 1 !important;
  transform: translateY(0) !important;
}

.search-category-header {
  padding: 8px 15px;
  background-color: var(--primary-color);
  color: var(--accent-color);
  font-weight: bold;
  font-size: 0.9rem;
  border-bottom: 1px solid var(--primary-dark);
}

.search-result-item {
  padding: 10px 15px;
  border-bottom: 1px solid var(--gray-light);
  cursor: pointer;
  transition: var(--transition);
  outline: none;
}

.search-result-item:hover,
.search-result-item:focus {
  background-color: var(--gray-light);
}

.search-result-title {
  font-weight: bold;
  margin-bottom: 4px;
  color: var(--primary-color);
}

.search-result-desc {
  font-size: 0.9rem;
  margin-bottom: 4px;
  color: var(--dark-color);
}

.search-result-meta {
  font-size: 0.8rem;
  color: var(--secondary-color);
}

.search-no-results {
  padding: 15px;
  text-align: center;
  color: var(--dark-color);
}

.search-no-results-message {
  margin-top: 6px;
  font-size: 0.85rem;
  color: var(--secondary-color);
}

/* 分类信息已由分组标题呈现，候选行不再重复渲染分类徽标（meta 去冗余） */

/* 首访一次性使用引导（参照 html-learning 参考页） */
.search-guide {
  padding: 12px 15px;
  background-color: #fdf3f8;
  border-bottom: 1px solid var(--gray-medium);
  display: flex;
  align-items: flex-start;
  gap: 12px;
  font-size: 0.9rem;
  color: var(--dark-color);
  line-height: 1.5;
}

.search-guide-body {
  flex: 1;
}

.search-guide-title {
  font-weight: bold;
  color: var(--primary-color);
  margin-bottom: 2px;
}

.search-guide-close {
  flex: none;
  background: none;
  border: 1px solid var(--gray-medium);
  border-radius: 4px;
  cursor: pointer;
  color: var(--primary-color);
  font-size: 1rem;
  line-height: 1;
  padding: 2px 8px;
}

.search-guide-close:hover,
.search-guide-close:focus {
  background-color: var(--primary-color);
  color: var(--accent-color);
  border-color: var(--primary-color);
}

/* combobox 键盘导航高亮：aria-selected 候选的视觉提示，与鼠标 hover/focus 区分 */
.search-result-item[aria-selected="true"],
.search-history-item[aria-selected="true"],
.search-popular-item[aria-selected="true"] {
  background-color: rgba(130, 37, 94, 0.12);
  outline: 2px solid rgba(130, 37, 94, 0.55);
}

/* 对视觉隐藏、供屏幕阅读器朗读的常驻状态区 */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

mark {
  background-color: #ffeb3b;
  color: #000;
  padding: 0 2px;
  border-radius: 2px;
}

.property-list {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
}

.property-item {
  width: 150px;
  margin: 5px;
  padding: 5px;
  text-align: center;
  background-color: var(--light-color);
}

.reference-section {
  background: var(--accent-color);
  padding: 1.5rem;
  border-radius: var(--border-radius);
  margin-bottom: 1.5rem;
  box-shadow: var(--shadow);
}

.quick-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 20px 0;
}

.quick-nav a {
  background: var(--primary-color);
  color: var(--accent-color);
  padding: 8px 16px;
  border-radius: var(--border-radius);
  text-decoration: none;
  font-size: 0.9rem;
  transition: var(--transition);
}

.quick-nav a:hover {
  background: var(--primary-dark);
}

.tag-badge {
  display: inline-block;
  background: var(--dark-color);
  color: var(--light-color);
  padding: 2px 8px;
  border-radius: 4px;
  font-family: "Courier New", Courier, monospace;
  font-size: 0.9rem;
  margin-right: 5px;
}

.compatibility-table,
.compatibility-table table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
}

.compatibility-table th,
.compatibility-table td {
  padding: 8px;
  text-align: center;
  border: 1px solid var(--gray-medium);
}

.compatibility-table th {
  background: var(--primary-color);
  color: var(--accent-color);
}

.supported {
  background: #d4edda;
  color: #155724;
}

.partial {
  background: #fff3cd;
  color: #856404;
}

.unsupported {
  background: #f8d7da;
  color: #721c24;
}

/* ---------- 底部（Footer） ---------- */
.footer-nav {
  background-color: var(--primary-color);
  padding: 1rem 0;
  box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.1);
}

footer {
  background-color: var(--dark-color);
  color: var(--light-color);
  text-align: center;
  padding: 1.25rem 1rem;
  border-radius: 0 0 var(--border-radius) var(--border-radius);
  box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.1);
}

footer p {
  margin: 0.5rem 0;
  font-size: 0.9rem;
}

footer a {
  color: var(--light-color);
  text-decoration: none;
  transition: var(--transition);
}

footer a:hover {
  text-decoration: underline;
  color: var(--accent-color);
}

/* ===== 5. 交互演示模块（Interactive Demos） ===== */
/* 顺序：CSS语法与选择器 → 盒模型 → 布局 → 定位 → Flexbox → Grid → 文本与字体 → 颜色与背景 → 响应式设计 → 过渡 → 动画 → 变换 → CSS变量 → 伪类 → 伪元素 → 高级CSS */

/* ---------- 通用交互演示（基础容器与控件） ---------- */
.interactive-demo {
  background-color: var(--white);
  padding: 1.5rem;
  border-radius: var(--border-radius);
  border: 1px solid var(--gray-medium);
  margin: 1rem 0;
}

.demo-controls {
  display: flex;
  gap: 1rem;
  margin-bottom: 1rem;
  flex-wrap: wrap;
}

.demo-button {
  background-color: var(--primary-color);
  color: var(--accent-color);
  border: none;
  padding: 0.5rem 1rem;
  border-radius: var(--border-radius);
  cursor: pointer;
  transition: var(--transition);
  font-family: inherit;
}

.demo-button:hover {
  background-color: var(--primary-dark);
}

.demo-output {
  background-color: var(--gray-light);
  padding: 1rem;
  border-radius: var(--border-radius);
  position: relative;
  min-height: 100px;
  overflow: auto;
}

.interactive-demo.enhanced {
  background-color: var(--white);
  border-radius: var(--border-radius);
  padding: 1.5rem;
  box-shadow: var(--shadow);
}

.demo-controls-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.5rem;
  margin-bottom: 1.5rem;
}

.control-group {
  background: var(--gray-light);
  padding: 1rem;
  border-radius: var(--border-radius);
  border-left: 4px solid var(--primary-color);
}

.control-group h4 {
  color: var(--primary-color);
  margin-bottom: 0.75rem;
  font-size: 1rem;
  border-bottom: 1px solid var(--gray-medium);
  padding-bottom: 0.5rem;
}

.control-group label {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin-bottom: 1rem;
  font-weight: 600;
  color: var(--dark-color);
}

.control-group input[type="range"] {
  width: 100%;
}

.control-group select {
  padding: 0.5rem;
  border: 1px solid var(--gray-medium);
  border-radius: 4px;
  font-family: inherit;
}

/* ---------- 1. CSS语法与选择器 ---------- */
.control-group .demo-button {
  display: block;
  width: 100%;
  margin-bottom: 0.5rem;
  text-align: left;
  padding: 0.5rem 0.75rem;
  font-size: 0.85rem;
  background: var(--primary-color);
  color: white;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  transition: all 0.3s ease;
}

.control-group .demo-button:hover {
  background: var(--primary-dark);
  transform: translateX(5px);
}

.demo-stats {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  margin-bottom: 1rem;
  padding: 1rem;
  background: var(--gray-light);
  border-radius: var(--border-radius);
  flex-wrap: wrap;
}

.stat-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

#currentSelector {
  background: var(--dark-color);
  color: var(--light-color);
  padding: 0.25rem 0.5rem;
  border-radius: 3px;
  font-family: "Courier New", Courier, monospace;
}

#matchCount {
  font-weight: bold;
  color: var(--primary-color);
  font-size: 1.1rem;
}

.demo-reset-btn {
  background: var(--secondary-color);
  color: white;
  border: none;
  padding: 0.5rem 1rem;
  border-radius: 4px;
  cursor: pointer;
  transition: var(--transition);
  margin-left: auto;
}

.demo-reset-btn:hover {
  background: var(--primary-dark);
}

.demo-content {
  padding: 1rem;
}

.demo-container {
  border: 2px dashed var(--gray-medium);
  padding: 1rem;
  margin: 1rem 0;
  border-radius: var(--border-radius);
  background: rgba(255, 255, 255, 0.5);
}

.demo-list {
  background: var(--white);
  padding: 1rem;
  border-radius: var(--border-radius);
  margin: 1rem 0;
}

.demo-list li {
  padding: 0.5rem;
  border-bottom: 1px solid var(--gray-light);
}

.demo-list li:last-child {
  border-bottom: none;
}

.demo-link {
  color: var(--primary-color);
  text-decoration: none;
}

.demo-link:hover {
  text-decoration: underline;
}

.demo-explanation {
  margin-top: 1.5rem;
  padding: 1rem;
  background: var(--gray-light);
  border-radius: var(--border-radius);
  border-left: 4px solid var(--primary-color);
}

.demo-explanation h4 {
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

#selectorExplanation {
  font-size: 0.9rem;
  line-height: 1.5;
}

.selector-highlight {
  position: relative;
  background: linear-gradient(135deg, #ffeb3b, #ff9800) !important;
  color: #000 !important;
  border: 2px solid #ff9800 !important;
  box-shadow: 0 0 0 4px rgba(255, 152, 0, 0.3) !important;
  z-index: 10;
  animation: pulse-highlight 0.6s ease;
}

.selector-hover-simulated {
  background: linear-gradient(135deg, #e3f2fd, #bbdefb) !important;
  color: #1565c0 !important;
  border: 2px solid #2196f3 !important;
  box-shadow: 0 0 0 4px rgba(33, 150, 243, 0.3) !important;
  text-decoration: underline !important;
  position: relative;
  z-index: 10;
}

.selector-info {
  position: absolute;
  background: var(--primary-color);
  color: white;
  padding: 4px 8px;
  border-radius: 4px;
  font-size: 0.75rem;
  z-index: 20;
  white-space: nowrap;
  pointer-events: none;
  top: -30px;
  left: 50%;
  transform: translateX(-50%);
  animation: fadeIn 0.3s ease;
}

.selector-info::after {
  content: "";
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  border: 5px solid transparent;
  border-top-color: var(--primary-color);
}

/* ---------- 2. 盒模型 ---------- */
.box-model-visualization {
  position: relative;
  margin: 2rem auto;
  max-width: 500px;
}

.margin-area {
  background-color: rgba(0, 0, 0, 0.05);
  padding: 30px;
  border: 1px dashed var(--secondary-color);
  position: relative;
  transition: all 0.2s ease;
  text-align: center;
}

.border-area {
  background-color: rgba(130, 37, 94, 0.1);
  padding: 5px;
  border: 5px solid var(--primary-color);
  position: relative;
  transition: all 0.2s ease;
  display: inline-block;
  width: auto;
  vertical-align: top;
}

.padding-area {
  background-color: rgba(209, 195, 157, 0.3);
  padding: 20px;
  position: relative;
  transition: all 0.2s ease;
}

.content-area {
  background-color: var(--primary-color);
  width: 200px;
  height: 100px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  font-weight: bold;
  color: var(--white);
  box-shadow: inset 0 0 5px rgba(0, 0, 0, 0.1);
  transition: all 0.2s ease;
}

.margin-label,
.border-label,
.padding-label,
.content-label {
  position: absolute;
  font-size: 0.8rem;
  font-weight: bold;
  color: var(--dark-color);
  background: rgba(255, 255, 255, 0.8);
  padding: 2px 6px;
  border-radius: 3px;
}

.margin-label {
  top: 3px;
  right: 120px;
  background-color: rgba(184, 59, 106, 0.2);
}

.border-label {
  top: 60px;
  right: -20px;
  background-color: rgba(130, 37, 94, 0.2);
}

.padding-label {
  top: -5px;
  right: 15px;
  background-color: rgba(209, 195, 157, 0.4);
}

.content-label {
  bottom: 60px;
  left: 60px;
}

.dimensions-info {
  background: var(--gray-light);
  padding: 1rem;
  border-radius: var(--border-radius);
  margin-top: 1rem;
}

.dimension-row {
  display: flex;
  justify-content: space-between;
  margin-bottom: 0.5rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--gray-medium);
}

.dimension-row:last-child {
  margin-bottom: 0;
  border-bottom: none;
}

.dimension-label {
  font-weight: 600;
  color: var(--dark-color);
}

/* ---------- 3. 布局（通用布局切换演示） ---------- */
.demo-info-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: var(--gray-light);
  padding: 1rem;
  border-radius: var(--border-radius);
  margin: 1rem 0;
  flex-wrap: wrap;
  gap: 1rem;
}

.info-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.info-label {
  font-weight: 600;
  color: var(--dark-color);
  font-size: 0.9rem;
}

#currentLayout,
#itemCount {
  background: var(--primary-color);
  color: white;
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 500;
}

.demo-output.enhanced {
  border: 2px dashed var(--gray-medium);
  background:
    linear-gradient(45deg, var(--gray-light) 25%, transparent 25%),
    linear-gradient(-45deg, var(--gray-light) 25%, transparent 25%),
    linear-gradient(45deg, transparent 75%, var(--gray-light) 75%),
    linear-gradient(-45deg, transparent 75%, var(--gray-light) 75%);
  background-size: 20px 20px;
  background-position:
    0 0,
    0 10px,
    10px -10px,
    -10px 0px;
  padding: 2rem;
  border-radius: var(--border-radius);
  min-height: 300px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.layout-demo-container {
  width: 100%;
  transition: all 0.3s ease;
}

.demo-item {
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  color: white;
  padding: 1rem;
  border-radius: 8px;
  margin: 5px;
  text-align: center;
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
  border: 2px solid transparent;
  box-sizing: border-box;
  min-width: unset;
}

.demo-item:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
  border-color: var(--accent-color);
}

.item-number {
  position: absolute;
  top: 5px;
  left: 5px;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 50%;
  width: 20px;
  height: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: bold;
}

.item-content {
  font-size: 0.9rem;
  opacity: 0.9;
}

.layout-float .demo-item {
  float: left;
  box-sizing: border-box;
}

.layout-float::after {
  content: "";
  display: table;
  clear: both;
}

.layout-multicol {
  column-gap: 20px;
}

.layout-multicol .demo-item {
  break-inside: avoid;
  margin-bottom: 10px;
  display: inline-block;
  width: 100%;
}

.layout-flex {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
}

.layout-flex .demo-item {
  flex: 1;
  min-width: 100px;
}

.layout-grid {
  display: grid;
  gap: 20px;
}

.layout-badge {
  display: inline-block;
  background: var(--primary-color);
  color: white;
  padding: 0.25rem 0.75rem;
  border-radius: 12px;
  font-size: 0.8rem;
  margin-left: 0.5rem;
  vertical-align: middle;
}

#layoutDemo.layout-demo-container {
  background-color: rgba(209, 195, 157, 0.15);
  border: 2px dashed var(--primary-color);
  transition:
    background-color 0.3s,
    border-color 0.3s;
}
#layoutDemo.layout-demo-container.clearfix-enabled {
  background-color: rgba(130, 37, 94, 0.3);
  border-color: var(--secondary-color);
  overflow: hidden;
}
.layout-float .demo-item {
  margin-bottom: 10px !important;
}

/* ---------- 4. 定位 ---------- */
.positioning-demo-container {
  position: relative;
  width: 100%;
  height: 500px;
  border: 2px dashed var(--gray-medium);
  background:
    linear-gradient(90deg, var(--gray-light) 1px, transparent 1px) 0 0 / 20px
      20px,
    linear-gradient(var(--gray-light) 1px, transparent 1px) 0 0 / 20px 20px;
  overflow: hidden;
  margin: 1rem 0;
}

.position-context-indicator {
  position: absolute;
  top: 20px;
  left: 20px;
  width: 200px;
  height: 150px;
  border: 2px solid var(--primary-color);
  background-color: rgba(130, 37, 94, 0.1);
  z-index: 0;
}

.context-label {
  position: absolute;
  top: -25px;
  left: 0;
  background-color: var(--primary-color);
  color: white;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.8rem;
  font-weight: 500;
}

.context-area {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary-color);
  font-size: 0.9rem;
  font-weight: 500;
}

.demo-element-container {
  position: relative;
  width: 100%;
  height: 100%;
}

.static-element,
.reference-element,
.overlay-element {
  position: absolute;
  width: 100px;
  height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 500;
  transition: all 0.3s ease;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
}

.static-element {
  top: 30px;
  left: 290px;
  background-color: var(--secondary-color);
  color: white;
  z-index: 0;
}

.reference-element {
  top: 110px;
  left: 150px;
  background-color: var(--accent-color);
  color: var(--dark-color);
  z-index: 0;
}

.overlay-element {
  top: 70px;
  left: 220px;
  background-color: rgba(184, 59, 106, 0.7);
  color: white;
  z-index: 0;
}

.fixed-hint {
  background-color: #fff3cd;
  border-left: 4px solid #ffc107;
  padding: 0.75rem 1rem;
  margin: 1rem 0;
  border-radius: 0 var(--border-radius) var(--border-radius) 0;
  color: #856404;
  font-weight: 500;
}

.position-demo-element {
  position: static;
  width: 120px;
  height: 100px;
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  color: white;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  transition: all 0.3s ease;
  z-index: 1;
  cursor: move;
  user-select: none;
  will-change: transform;
}

.position-demo-element:hover {
  transform: scale(1.05);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.2);
}

.element-content {
  padding: 10px;
  text-align: center;
}

.element-coordinates,
.element-zindex {
  font-size: 0.7rem;
  margin-top: 5px;
  opacity: 0.9;
  font-family: "Courier New", monospace;
}

.element-coordinates {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.scroll-content {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 200px;
  overflow-y: auto;
  background-color: rgba(255, 255, 255, 0.95);
  border-top: 2px solid var(--gray-medium);
  z-index: 2;
}

.scroll-indicator {
  padding: 12px;
  background-color: var(--primary-color);
  color: white;
  text-align: center;
  font-size: 0.9rem;
  font-weight: 500;
  position: sticky;
  top: 0;
  z-index: 10;
}

.scroll-item {
  padding: 20px;
  border-bottom: 1px solid var(--gray-light);
  height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: white;
  transition: background-color 0.3s ease;
}

.scroll-item:nth-child(even) {
  background-color: var(--gray-light);
}

.scroll-item:hover {
  background-color: rgba(130, 37, 94, 0.1);
}

.z-index-visual {
  display: flex;
  flex-direction: column;
  gap: 5px;
  margin-top: 10px;
  border: 1px solid var(--gray-medium);
  padding: 10px;
  border-radius: var(--border-radius);
  background: var(--gray-light);
}

.z-layer {
  padding: 8px 12px;
  background-color: var(--white);
  border-radius: 4px;
  text-align: center;
  font-size: 0.8rem;
  transition: all 0.3s ease;
  opacity: 0.6;
  border: 1px solid var(--gray-medium);
}

.z-layer.active {
  background-color: var(--primary-color);
  color: white;
  opacity: 1;
  transform: scale(1.05);
  border-color: var(--primary-dark);
}

.control-description {
  font-size: 0.8rem;
  color: var(--dark-color);
  margin-top: 5px;
  font-style: italic;
  line-height: 1.4;
}

.position-demo-element.position-static {
  background: rgba(0, 0, 0, 0.5);
}

.position-demo-element.position-relative {
  background: rgba(0, 0, 255, 0.6);
}

.position-demo-element.position-absolute {
  background: rgba(0, 255, 0, 0.7);
}

.position-demo-element.position-fixed {
  background: linear-gradient(135deg, #ffc107, #e0a800);
  color: var(--dark-color);
}

.position-demo-element.position-sticky {
  background: linear-gradient(135deg, #dc3545, #b02a37);
}

.position-demo-element.dragging {
  cursor: grabbing;
  transform: scale(1.1);
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.3);
  z-index: 1000;
}

/* ---------- 5. Flexbox 演示 ---------- */
.flex-demo {
  display: flex;
  background-color: var(--light-color);
  padding: 1rem;
  border-radius: var(--border-radius);
  margin: 1rem 0;
  min-height: 150px;
  border: 2px dashed var(--primary-color);
  transition: all 0.3s ease;
}

.flex-item {
  background-color: var(--primary-color);
  color: var(--accent-color);
  padding: 1rem;
  border-radius: var(--border-radius);
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  font-weight: 500;
  transition: var(--transition);
  min-width: 80px;
  min-height: 60px;
  margin: 5px;
  border: 2px solid var(--primary-dark);
}

.flex-item:hover {
  background-color: var(--primary-dark);
  transform: scale(1.05);
}

.flex-item:nth-child(1) {
  background-color: #82255e;
}
.flex-item:nth-child(2) {
  background-color: #b83b6a;
}
.flex-item:nth-child(3) {
  background-color: #d1c39d;
  color: var(--dark-color);
}
.flex-item:nth-child(4) {
  background-color: #2a101b;
}
.flex-item:nth-child(5) {
  background-color: #6a1e4c;
}

.flex-controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.flex-control-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.flex-control-group label {
  font-weight: 600;
  color: var(--dark-color);
  font-size: 0.9rem;
}

.flex-control-group select {
  padding: 0.5rem;
  border: 1px solid var(--gray-medium);
  border-radius: 4px;
  font-family: inherit;
  background-color: white;
}

.flex-control-group select:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 2px rgba(130, 37, 94, 0.2);
}

.flex-demo-enhanced {
  display: flex;
  background-color: var(--light-color);
  padding: 1.5rem;
  border-radius: var(--border-radius);
  margin: 1rem 0;
  min-height: 200px;
  border: 2px dashed var(--primary-color);
  transition: all 0.3s ease;
  width: 600px;
  margin: 0 auto;
  position: relative;
  background-image:
    linear-gradient(90deg, var(--gray-medium) 1px, transparent 1px),
    linear-gradient(var(--gray-medium) 1px, transparent 1px);
  background-size: 20px 20px;
  background-position: center center;
}

.flex-item-enhanced {
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  color: white;
  padding: 1rem;
  border-radius: var(--border-radius);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  font-weight: 500;
  transition: all 0.3s ease;
  min-width: 100px;
  min-height: 80px;
  border: 2px solid var(--primary-dark);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
  position: relative;
  overflow: hidden;
}

.flex-item-enhanced:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.25);
  z-index: 10;
}

.flex-item-enhanced::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent-color), transparent);
}

.flex-item-number {
  position: absolute;
  top: 5px;
  left: 5px;
  background: rgba(255, 255, 255, 0.9);
  color: var(--dark-color);
  border-radius: 50%;
  width: 20px;
  height: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  font-weight: bold;
}

.flex-item-size {
  font-size: 0.7rem;
  margin-top: 5px;
  opacity: 0.9;
  background: rgba(0, 0, 0, 0.2);
  padding: 2px 6px;
  border-radius: 3px;
}

.flex-item-enhanced:nth-child(1) {
  background: linear-gradient(135deg, #82255e, #b83b6a);
}
.flex-item-enhanced:nth-child(2) {
  background: linear-gradient(135deg, #b83b6a, #d1c39d);
}
.flex-item-enhanced:nth-child(3) {
  background: linear-gradient(135deg, #d1c39d, #2a101b);
  color: var(--accent-color);
}
.flex-item-enhanced:nth-child(4) {
  background: linear-gradient(135deg, #2a101b, #6a1e4c);
}
.flex-item-enhanced:nth-child(5) {
  background: linear-gradient(135deg, #6a1e4c, #82255e);
}
.flex-item-enhanced:nth-child(6) {
  background: linear-gradient(135deg, #9c366b, #b83b6a);
}
.flex-item-enhanced:nth-child(7) {
  background: linear-gradient(135deg, #c94c7a, #d1c39d);
  color: var(--dark-color);
}
.flex-item-enhanced:nth-child(8) {
  background: linear-gradient(135deg, #e8a5b8, #2a101b);
}
.flex-item-enhanced:nth-child(9) {
  background: linear-gradient(135deg, #2a101b, #6a1e4c);
}
.flex-item-enhanced:nth-child(10) {
  background: linear-gradient(135deg, #6a1e4c, #82255e);
}
.flex-item-enhanced:nth-child(11) {
  background: linear-gradient(135deg, #82255e, #b83b6a);
}
.flex-item-enhanced:nth-child(12) {
  background: linear-gradient(135deg, #b83b6a, #d1c39d);
  color: var(--dark-color);
}

.axis-indicator {
  position: absolute;
  pointer-events: none;
  z-index: 5;
}

.main-axis {
  border-top: 2px solid var(--primary-color);
  width: 100%;
  top: 50%;
  transform: translateY(-50%);
}

.cross-axis {
  border-left: 2px solid var(--secondary-color);
  height: 100%;
  left: 50%;
  transform: translateX(-50%);
}

.axis-label {
  position: absolute;
  background: var(--primary-color);
  color: white;
  padding: 2px 6px;
  border-radius: 3px;
  font-size: 0.7rem;
  font-weight: bold;
}

.main-axis-label {
  top: -25px;
  left: 10px;
}

.cross-axis-label {
  top: 10px;
  left: -35px;
  transform: rotate(-90deg);
  background: var(--secondary-color);
}

.demo-code-preview {
  margin-top: 1.5rem;
  padding: 1rem;
  background: var(--gray-light);
  border-radius: var(--border-radius);
  border-left: 4px solid var(--primary-color);
}

.demo-code-preview h4 {
  color: var(--primary-color);
  margin-bottom: 0.75rem;
  font-size: 1rem;
}

.demo-code-preview pre {
  background: var(--dark-color);
  color: var(--light-color);
  padding: 1rem;
  border-radius: var(--border-radius);
  overflow-x: auto;
  font-family: "Courier New", Courier, monospace;
  font-size: 0.9rem;
  margin-bottom: 0.75rem;
}

.flex-item-enhanced.selected-item {
  outline: 3px solid var(--accent-color);
  outline-offset: 2px;
  box-shadow: 0 0 15px rgba(209, 195, 157, 0.6);
  z-index: 20;
  transform: scale(1.02);
}
.selected-item-code {
  margin-top: 1.5rem;
  padding-top: 0.5rem;
  border-top: 1px dashed var(--gray-medium);
}
.selected-item-code h4 {
  color: var(--primary-color);
  margin-bottom: 0.75rem;
  font-size: 1rem;
}

/* ---------- 6. Grid 演示 ---------- */
.grid-demo {
  display: grid;
  background-color: var(--light-color);
  padding: 1.5rem;
  border-radius: var(--border-radius);
  margin: 1rem 0;
  min-height: 300px;
  border: 2px dashed var(--primary-color);
  transition: all 0.3s ease;
  background-image:
    linear-gradient(90deg, var(--gray-medium) 1px, transparent 1px),
    linear-gradient(var(--gray-medium) 1px, transparent 1px);
  background-size: 20px 20px;
  background-position: center center;
}

.grid-item {
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  color: white;
  padding: 1rem;
  border-radius: var(--border-radius);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  font-weight: 500;
  transition: all 0.3s ease;
  min-height: 80px;
  border: 2px solid var(--primary-dark);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
  position: relative;
  overflow: hidden;
}

.grid-item:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.25);
  z-index: 10;
}

.grid-item::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent-color), transparent);
}

.grid-item .item-number {
  position: absolute;
  top: 5px;
  left: 5px;
  background: rgba(255, 255, 255, 0.9);
  color: var(--dark-color);
  border-radius: 50%;
  width: 20px;
  height: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  font-weight: bold;
}

.grid-item:nth-child(1) {
  background: linear-gradient(135deg, #82255e, #b83b6a);
}
.grid-item:nth-child(2) {
  background: linear-gradient(135deg, #b83b6a, #d1c39d);
}
.grid-item:nth-child(3) {
  background: linear-gradient(135deg, #d1c39d, #2a101b);
  color: var(--accent-color);
}
.grid-item:nth-child(4) {
  background: linear-gradient(135deg, #2a101b, #6a1e4c);
}
.grid-item:nth-child(5) {
  background: linear-gradient(135deg, #6a1e4c, #82255e);
}
.grid-item:nth-child(6) {
  background: linear-gradient(135deg, #9c366b, #b83b6a);
}

.grid-controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.grid-control-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.grid-control-group label {
  font-weight: 600;
  color: var(--dark-color);
  font-size: 0.9rem;
}

.grid-control-group input,
.grid-control-group select {
  padding: 0.5rem;
  border: 1px solid var(--gray-medium);
  border-radius: 4px;
  font-family: inherit;
}

.grid-control-group input:focus,
.grid-control-group select:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 2px rgba(130, 37, 94, 0.2);
}

.demo-buttons {
  display: flex;
  gap: 1rem;
  margin: 1rem 0;
  flex-wrap: wrap;
}

/* ---------- 7. 文本与字体 ---------- */
.typography-demo-content {
  padding: 2rem;
  background: white;
  border-radius: var(--border-radius);
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  max-width: 800px;
  margin: 0 auto;
}

.demo-title {
  color: var(--primary-color);
  margin-bottom: 1.5rem;
  border-bottom: 2px solid var(--primary-color);
  padding-bottom: 0.5rem;
}

.demo-paragraph {
  margin-bottom: 1.5rem;
  line-height: inherit;
  text-align: inherit;
}

.demo-quote {
  border-left: 4px solid var(--secondary-color);
  padding-left: 1rem;
  margin: 1.5rem 0;
  font-style: italic;
  color: var(--dark-color);
  background: var(--gray-light);
  padding: 1rem;
  border-radius: 0 var(--border-radius) var(--border-radius) 0;
}

.value-display {
  display: inline-block;
  min-width: 50px;
  text-align: right;
  font-weight: 600;
  color: var(--primary-color);
}

#fontPreview {
  transition: all 0.2s ease;
  border: 1px dashed var(--primary-color);
  background-color: var(--gray-light);
  color: var(--dark-color);
}

/* ---------- 8. 颜色与背景 ---------- */
.variable-demo-item {
  padding: var(--demo-spacing);
  background-color: var(--demo-primary);
  color: white;
  border-radius: var(--demo-radius);
  box-shadow: 0 var(--demo-shadow) var(--demo-shadow) rgba(0, 0, 0, 0.3);
  margin: var(--demo-spacing) 0;
  font-size: var(--demo-font-size);
  transition: all 0.3s ease;
  position: relative;
  min-height: 80px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
}

.variable-demo-item .item-number,
.variable-demo-item .item-content,
.variable-demo-item .element-properties {
  font-size: inherit;
}

.variable-demo-item.secondary {
  background-color: var(--accent-color);
  color: var(--dark-color);
}

.color-preview {
  width: 100%;
  height: 30px;
  border: 1px solid var(--gray-medium);
  border-radius: 4px;
  margin-top: 5px;
}

.color-info {
  font-size: 0.9rem;
}

.color-info p {
  margin: 0.5rem 0;
  font-family: "Courier New", monospace;
  background: var(--gray-light);
  padding: 0.5rem;
  border-radius: 4px;
  border-left: 3px solid var(--primary-color);
}

.demo-output.enhanced #backgroundDemo {
  padding: 2rem;
  text-align: center;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  min-height: 200px;
  transition: all 0.3s ease;
}

.demo-output.enhanced #backgroundDemo h4 {
  margin-bottom: 1rem;
  color: inherit;
  font-size: 1.5rem;
}

.demo-output.enhanced #backgroundDemo p {
  margin: 0.5rem 0;
  line-height: 1.6;
}

/* ---------- 9. 响应式设计演示 ---------- */
.responsive-demo-container {
  width: 800px;
  max-width: 100%;
  margin: 0 auto;
  background: white;
  border: 1px solid var(--gray-medium);
  transition: all 0.3s ease;
  position: relative;
}

.responsive-demo-container.mobile-view {
  width: 375px;
  border: 2px solid var(--primary-color);
  box-shadow: 0 0 20px rgba(130, 37, 94, 0.3);
  border-radius: 12px;
  overflow: hidden;
}

.responsive-demo-container.tablet-view {
  width: 768px;
  border: 2px solid var(--secondary-color);
  box-shadow: 0 0 20px rgba(184, 59, 106, 0.3);
  border-radius: 8px;
  overflow: hidden;
}

.demo-header {
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  color: white;
  padding: 1.5rem;
  text-align: center;
}

.demo-header h4 {
  margin: 0 0 0.5rem 0;
  font-size: 1.5rem;
}

.demo-header p {
  margin: 0;
  opacity: 0.9;
}

.demo-content {
  display: flex;
  padding: 1.5rem;
  gap: 2rem;
  min-height: 300px;
}

.layout-fluid .demo-content {
  flex-wrap: wrap;
}

.layout-fluid .content-section {
  flex: 2;
  min-width: 300px;
}

.layout-fluid .sidebar-section {
  flex: 1;
  min-width: 250px;
}

.layout-flexbox .demo-content {
  display: flex;
  flex-wrap: wrap;
}

.layout-flexbox .content-section {
  flex: 2 1 600px;
}

.layout-flexbox .sidebar-section {
  flex: 1 1 300px;
}

.layout-grid .demo-content {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 2rem;
}

.layout-float .demo-content {
  overflow: hidden;
}

.layout-float .content-section {
  float: left;
  width: 66.66%;
  margin-right: 2rem;
}

.layout-float .sidebar-section {
  float: left;
  width: calc(33.33% - 2rem);
}

@media (max-width: 640px) {
  .layout-float .content-section,
  .layout-float .sidebar-section {
    float: none !important;
    width: 100% !important;
    margin-right: 0 !important;
    margin-bottom: 1.5rem;
  }
  .layout-float .demo-content {
    overflow: visible;
  }
}

.sidebar-section {
  background: var(--accent-color);
  color: var(--dark-color);
  padding: 1.5rem;
  border-radius: var(--border-radius);
  border-left: 4px solid var(--secondary-color);
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 1rem;
  margin-top: 1rem;
}

.feature-item {
  background: white;
  padding: 1rem;
  border-radius: var(--border-radius);
  text-align: center;
  border: 1px solid var(--gray-medium);
  transition: all 0.3s ease;
}

.feature-item:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.demo-footer {
  background: var(--dark-color);
  color: white;
  padding: 1rem;
  text-align: center;
  border-top: 1px solid var(--gray-medium);
}

.media-queries-info {
  margin-top: 1.5rem;
  padding: 1rem;
  background: var(--gray-light);
  border-radius: var(--border-radius);
  border-left: 4px solid var(--primary-color);
}

.media-queries-info h4 {
  color: var(--primary-color);
  margin-bottom: 0.75rem;
}

.media-query-item {
  background: white;
  padding: 0.75rem;
  margin: 0.5rem 0;
  border-radius: 4px;
  border-left: 3px solid var(--secondary-color);
  font-family: "Courier New", monospace;
  font-size: 0.9rem;
}

.media-query-item.active {
  background: var(--primary-color);
  color: white;
  border-left-color: var(--accent-color);
}

.breakpoint-indicator {
  position: absolute;
  top: 0;
  right: 0;
  background: var(--primary-color);
  color: white;
  padding: 0.25rem 0.75rem;
  border-radius: 0 0 0 4px;
  font-size: 0.8rem;
  font-weight: 500;
}

.responsive-text {
  font-size: clamp(1rem, 2.5vw, 1.5rem);
  line-height: 1.6;
}

.device-frame {
  position: relative;
  background: #f0f0f0;
  border-radius: 12px;
  padding: 20px;
  margin: 0 auto;
}

.device-frame::before {
  content: "";
  position: absolute;
  top: -10px;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 6px;
  background: #ccc;
  border-radius: 3px;
}

/* ---------- 10. 过渡效果演示 ---------- */
.transition-demo-element {
  width: 100px;
  height: 100px;
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  color: white;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  cursor: pointer;
  user-select: none;
  margin: 0 auto;
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
}

.transition-demo-element[data-transition-type="background-color"],
.transition-demo-element[data-transition-type="all"] {
  background: var(--primary-color) !important;
  background-image: none !important;
}

.transition-demo-element:hover {
  transform: scale(1.05);
}

.transition-demo-element::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent-color), transparent);
}

.element-properties {
  font-size: 0.7rem;
  margin-top: 5px;
  opacity: 0.9;
  font-family: "Courier New", monospace;
}

.demo-events {
  margin-top: 1.5rem;
  padding: 1rem;
  background: var(--gray-light);
  border-radius: var(--border-radius);
  border-left: 4px solid var(--primary-color);
}

.demo-events h4 {
  color: var(--primary-color);
  margin-bottom: 0.75rem;
  font-size: 1rem;
}

.events-log {
  background: var(--dark-color);
  color: var(--light-color);
  padding: 1rem;
  border-radius: var(--border-radius);
  font-family: "Courier New", Courier, monospace;
  font-size: 0.8rem;
  max-height: 150px;
  overflow-y: auto;
  line-height: 1.4;
}

.events-log div {
  padding: 2px 0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.events-log div:last-child {
  border-bottom: none;
}

#transitionState {
  background: var(--primary-color);
  color: white;
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 500;
}

#transitionState.transitioning {
  background: var(--secondary-color);
  animation: pulse 1s infinite;
}

/* ---------- 11. 动画效果演示 ---------- */
@keyframes pulse-highlight {
  0% {
    transform: scale(1);
    box-shadow: 0 0 0 0 rgba(255, 152, 0, 0.7);
  }
  50% {
    transform: scale(1.02);
    box-shadow: 0 0 0 10px rgba(255, 152, 0, 0);
  }
  100% {
    transform: scale(1);
    box-shadow: 0 0 0 0 rgba(255, 152, 0, 0);
  }
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

@keyframes bounce {
  0%,
  20%,
  50%,
  80%,
  100% {
    transform: translateY(0);
  }
  40% {
    transform: translateY(-30px);
  }
  60% {
    transform: translateY(-15px);
  }
}

@keyframes slideIn {
  from {
    transform: translateX(-100px);
    opacity: 0;
  }
  to {
    transform: translateX(0);
    opacity: 1;
  }
}

@keyframes rotate {
  from {
    transform: rotate(0deg);
  }
  to {
    transform: rotate(360deg);
  }
}

@keyframes pulse {
  0% {
    transform: scale(1);
    opacity: 1;
  }
  50% {
    transform: scale(1.1);
    opacity: 0.7;
  }
  100% {
    transform: scale(1);
    opacity: 1;
  }
}

@keyframes shake {
  0%,
  100% {
    transform: translateX(0);
  }
  10%,
  30%,
  50%,
  70%,
  90% {
    transform: translateX(-10px);
  }
  20%,
  40%,
  60%,
  80% {
    transform: translateX(10px);
  }
}

@keyframes flip {
  0% {
    transform: perspective(400px) rotateY(0);
  }
  50% {
    transform: perspective(400px) rotateY(180deg);
  }
  100% {
    transform: perspective(400px) rotateY(360deg);
  }
}

@keyframes zoom {
  0% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.2);
  }
  100% {
    transform: scale(1);
  }
}

#animationDemo {
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: bold;
  cursor: pointer;
}

#animationDemo.running::after {
  content: "▶";
  position: absolute;
  bottom: 5px;
  right: 5px;
  font-size: 12px;
  color: rgba(255, 255, 255, 0.8);
}

#animationDemo.paused::after {
  content: "⏸";
  position: absolute;
  bottom: 5px;
  right: 5px;
  font-size: 12px;
  color: rgba(255, 255, 255, 0.8);
}

#animationEvents {
  transition: all 0.3s ease;
  min-height: 40px;
  font-family: "Courier New", monospace;
}

.animation-event {
  padding: 5px 8px;
  margin: 2px 0;
  border-radius: 3px;
  font-size: 0.85rem;
  animation: fadeIn 0.3s ease;
}

.animation-event.start {
  background: rgba(76, 175, 80, 0.2);
  border-left: 3px solid #4caf50;
}
.animation-event.end {
  background: rgba(244, 67, 54, 0.2);
  border-left: 3px solid #f44336;
}
.animation-event.iteration {
  background: rgba(33, 150, 243, 0.2);
  border-left: 3px solid #2196f3;
}
.animation-event.cancel {
  background: rgba(255, 152, 0, 0.2);
  border-left: 3px solid #ff9800;
}

#basicAnimation {
  width: 100px;
  height: 100px;
  margin: 20px auto;
  border-radius: var(--border-radius);
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.2);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: bold;
  font-size: 1.2rem;
  animation: pulse 2s infinite ease-in-out;
}

/* ---------- 12. 变换效果演示 ---------- */
#transformContainer {
  position: relative;
  min-height: 400px;
  display: flex;
  align-items: center;
  justify-content: center;
  background:
    radial-gradient(
      circle at 20% 20%,
      rgba(130, 37, 94, 0.1) 0%,
      transparent 50%
    ),
    radial-gradient(
      circle at 80% 80%,
      rgba(184, 59, 106, 0.1) 0%,
      transparent 50%
    );
  border-radius: var(--border-radius);
  overflow: hidden;
  padding: 20px;
}

#transformContainer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-image:
    linear-gradient(rgba(130, 37, 94, 0.1) 1px, transparent 1px),
    linear-gradient(90deg, rgba(130, 37, 94, 0.1) 1px, transparent 1px);
  background-size: 20px 20px;
  opacity: 0.5;
}

.transform-demo-element {
  width: 180px;
  height: 180px;
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  color: white;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
  transition: all 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  position: relative;
  overflow: hidden;
  cursor: pointer;
  border: 3px solid rgba(255, 255, 255, 0.1);
}

.transform-demo-element::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--accent-color), transparent);
}

.transform-demo-element:hover {
  box-shadow: 0 12px 35px rgba(0, 0, 0, 0.3);
}

#transformContainer.preserve-3d .transform-demo-element {
  background: linear-gradient(135deg, #82255e, #b83b6a);
  border: 3px solid rgba(255, 255, 255, 0.2);
}

.transform-demo-element.backface-hidden {
  backface-visibility: hidden;
}

#transformContainer .axis-indicator {
  position: absolute;
  pointer-events: none;
  z-index: 10;
}

#transformContainer .x-axis {
  width: 100%;
  height: 2px;
  background: linear-gradient(90deg, transparent, #ff5555, transparent);
  top: 50%;
  left: 0;
  transform: translateY(-50%);
  opacity: 0.7;
}

#transformContainer .y-axis {
  width: 2px;
  height: 100%;
  background: linear-gradient(180deg, transparent, #55ff55, transparent);
  left: 50%;
  top: 0;
  transform: translateX(-50%);
  opacity: 0.7;
}

#transformContainer .z-axis {
  width: 60px;
  height: 60px;
  border: 3px solid #5555ff;
  border-radius: 50%;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  opacity: 0.7;
  box-shadow: 0 0 15px rgba(85, 85, 255, 0.6);
  background: transparent;
}

#transformContainer .z-axis.z-axis-circle {
  width: 60px !important;
  height: 60px !important;
  border: 3px solid #5555ff !important;
  border-radius: 50% !important;
  background: transparent !important;
  opacity: 0.9 !important;
  box-shadow: 0 0 15px rgba(85, 85, 255, 0.6);
}

#transformContainer .axis-label-x {
  position: absolute;
  right: 10px;
  top: -20px;
  background: #ff5555;
  color: white;
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 12px;
  font-weight: bold;
}

#transformContainer .axis-label-y {
  position: absolute;
  bottom: 10px;
  left: -25px;
  background: #55aa55;
  color: white;
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 12px;
  font-weight: bold;
  transform: rotate(-90deg);
  transform-origin: left top;
}

#transformContainer .axis-label-z {
  position: absolute;
  top: -25px;
  left: 50%;
  transform: translateX(-50%);
  background: #5555ff;
  color: white;
  padding: 2px 8px;
  border-radius: 12px;
  font-size: 12px;
  font-weight: bold;
  white-space: nowrap;
}

#transformContainer .x-axis.highlight {
  opacity: 1;
  background: linear-gradient(90deg, transparent, #ff0000, transparent);
  filter: drop-shadow(0 0 6px #ff5555);
}

#transformContainer .y-axis.highlight {
  opacity: 1;
  background: linear-gradient(180deg, transparent, #00ff00, transparent);
  filter: drop-shadow(0 0 6px #55ff55);
}

#transformContainer .z-axis.highlight {
  opacity: 1;
  border-color: #3333ff;
  box-shadow: 0 0 20px #5555ff;
}

#transformContainer .axis-indicator.hidden {
  display: none;
}

.element-content {
  padding: 20px;
  text-align: center;
  z-index: 2;
  position: relative;
}

.element-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 10px;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.control-hint {
  display: inline-block;
  margin-left: 8px;
  font-size: 0.75rem;
  font-weight: 600;
  color: #ffffff;
  background-color: var(--secondary-color);
  padding: 2px 8px;
  border-radius: 12px;
  white-space: nowrap;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

#perspectiveControl.disabled-control {
  opacity: 0.6;
  pointer-events: none;
  position: relative;
  background-color: rgba(0, 0, 0, 0.02);
  border-radius: 6px;
  padding: 8px;
  margin: -8px;
  transition: opacity 0.2s;
}

#perspectiveControl.disabled-control::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: repeating-linear-gradient(
    45deg,
    rgba(150, 150, 150, 0.15) 0px,
    rgba(150, 150, 150, 0.15) 4px,
    transparent 4px,
    transparent 8px
  );
  border-radius: 4px;
  pointer-events: none;
  z-index: 1;
}

#transformPerspective:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  filter: grayscale(0.5);
}

label:has(#transformZ:disabled) {
  opacity: 0.7;
  background-color: rgba(0, 0, 0, 0.02);
  border-radius: 4px;
  padding: 6px;
  margin: -6px;
}

#perspectiveHint {
  margin-left: 8px;
  font-size: 0.8rem;
  color: var(--secondary-color);
  background: rgba(184, 59, 106, 0.1);
  padding: 2px 8px;
  border-radius: 12px;
  font-weight: 500;
  transition: all 0.2s ease;
}

#perspectiveControl.disabled-control #perspectiveHint {
  background: #dc3545;
  color: white;
  font-weight: 600;
}

#yDisabledHint {
  display: inline-block;
  margin-left: 8px;
  font-size: 0.75rem;
  font-weight: 600;
  color: #ffffff;
  background-color: var(--secondary-color);
  padding: 2px 8px;
  border-radius: 12px;
  white-space: nowrap;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.info-item span[id="currentTransform"] {
  display: inline-block;
  max-width: 200px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  vertical-align: middle;
  cursor: help;
}

.control-group label.checkbox-label {
  flex-direction: row;
  align-items: center;
  gap: 8px;
  cursor: pointer;
}

.control-group label.checkbox-label input[type="checkbox"] {
  width: auto;
  margin: 0;
  cursor: pointer;
}

input[type="range"] {
  height: 8px;
  -webkit-appearance: none;
  appearance: none;
  background: var(--gray-medium);
  border-radius: 4px;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 24px;
  height: 24px;
  background: var(--primary-color);
  border-radius: 50%;
  cursor: pointer;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
  border: 2px solid white;
}

input[type="range"]::-moz-range-thumb {
  width: 24px;
  height: 24px;
  background: var(--primary-color);
  border-radius: 50%;
  cursor: pointer;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
  border: 2px solid white;
}

input[type="range"]::-moz-range-track {
  height: 8px;
  background: var(--gray-medium);
  border-radius: 4px;
}

input[type="range"]:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* ---------- 13. CSS变量演示 ---------- */
/* 主要样式已包含在颜色与背景部分的 .variable-demo-item 中 */

/* ---------- 14. 伪类演示 ---------- */
.demo-container[data-demo-state="active"] {
  border: 2px solid var(--primary-color);
  background: rgba(130, 37, 94, 0.05);
}

.demo-controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
  margin-bottom: 1.5rem;
}

@media (max-width: 576px) {
  .demo-controls {
    grid-template-columns: 1fr !important;
  }
}

.demo-info-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: var(--gray-light);
  padding: 1rem;
  border-radius: var(--border-radius);
  margin: 1rem 0;
  flex-wrap: wrap;
  gap: 1rem;
}

.info-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.info-label {
  font-weight: 600;
  color: var(--dark-color);
  font-size: 0.9rem;
}

#demoState,
#activeEffect {
  background: var(--primary-color);
  color: white;
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 500;
}

#demoState.active {
  background: var(--secondary-color);
}

#pseudoClassDemo {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: center;
  padding: 1.5rem;
}

#pseudoClassDemo .demo-item {
  width: 100px;
  height: 100px;
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  color: white;
  border-radius: var(--border-radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 1rem;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  transition: all 0.3s ease;
  cursor: pointer;
  user-select: none;
  position: relative;
  overflow: hidden;
  border: 2px solid transparent;
}

#pseudoClassDemo .demo-item::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent-color), transparent);
}

#pseudoClassDemo .demo-item:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.2);
}

.form-demo-section {
  margin-top: 2rem;
  padding: 1.5rem;
  background: white;
  border-radius: var(--border-radius);
  border: 1px solid var(--gray-medium);
}

.form-demo-section h4 {
  color: var(--primary-color);
  margin-bottom: 1rem;
  border-bottom: 2px solid var(--primary-color);
  padding-bottom: 0.5rem;
}

.demo-input {
  padding: 0.75rem;
  border: 2px solid var(--gray-medium);
  border-radius: var(--border-radius);
  font-family: inherit;
  transition: all 0.3s ease;
  width: 100%;
  max-width: 300px;
}

.demo-input:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(130, 37, 94, 0.1);
}

.checkbox-label {
  cursor: pointer;
  transition: all 0.3s ease;
  padding: 0.5rem;
  border-radius: 4px;
}

.demo-checkbox:checked + .checkbox-label {
  font-weight: 600;
}

.demo-checkbox:checked {
  outline: 3px solid var(--primary-color);
  outline-offset: 2px;
  accent-color: var(--primary-color);
}

.demo-checkbox:checked + .checkbox-label {
  font-weight: 700;
  color: var(--primary-color);
  background-color: rgba(130, 37, 94, 0.08);
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  transition: all 0.2s ease;
}

.focus-within-demo {
  margin-top: 1.5rem;
  padding: 1rem;
  background: #fafafa;
  border-radius: var(--border-radius);
  border: 2px dashed var(--gray-medium);
  transition: all 0.2s;
}

.focus-within-demo:focus-within {
  border-color: var(--primary-color);
  background: rgba(130, 37, 94, 0.03);
  box-shadow: 0 0 0 3px rgba(130, 37, 94, 0.1);
}

.focus-within-demo p {
  margin: 0 0 8px 0;
  font-weight: 500;
  color: var(--dark-color);
}

.demo-controls-hint {
  text-align: center;
  margin: 1rem 0;
  padding: 1rem;
  background: rgba(209, 195, 157, 0.1);
  border-radius: var(--border-radius);
  border-left: 4px solid var(--accent-color);
}

.demo-controls-hint p {
  margin: 0;
  color: var(--dark-color);
  font-size: 0.9rem;
}

.demo-button.secondary {
  background: var(--accent-color);
  color: var(--dark-color);
}

.demo-button.secondary:hover {
  background: #c4b48c;
}

.demo-hover-active.demo-style-color {
  color: #ff6b6b !important;
  background-color: #ffecec !important;
}
.demo-hover-active.demo-style-transform {
  transform: scale(1.1) rotate(5deg) !important;
}
.demo-hover-active.demo-style-background {
  background: linear-gradient(
    45deg,
    var(--primary-color),
    var(--secondary-color)
  ) !important;
}
.demo-hover-active.demo-style-border {
  border: 3px solid var(--accent-color) !important;
  box-shadow: 0 0 10px rgba(209, 195, 157, 0.5) !important;
}

.demo-active-active.demo-style-color {
  color: white !important;
  background-color: #e74c3c !important;
}
.demo-active-active.demo-style-transform {
  transform: scale(0.9) !important;
}
.demo-active-active.demo-style-background {
  background: linear-gradient(45deg, #c0392b, #e74c3c) !important;
}
.demo-active-active.demo-style-border {
  border: 3px solid #e74c3c !important;
  box-shadow: inset 0 0 10px rgba(0, 0, 0, 0.2) !important;
}

.demo-focus-active.demo-style-color {
  color: white !important;
  background-color: #3498db !important;
}
.demo-focus-active.demo-style-transform {
  transform: scale(1.05) !important;
  outline: 3px solid #3498db !important;
}
.demo-focus-active.demo-style-background {
  background: linear-gradient(45deg, #2980b9, #3498db) !important;
}
.demo-focus-active.demo-style-border {
  border: 3px solid #3498db !important;
  box-shadow: 0 0 15px rgba(52, 152, 219, 0.5) !important;
  outline: none !important;
}

.demo-nth-child-match {
  border: 4px solid var(--accent-color) !important;
  box-shadow: 0 0 15px rgba(209, 195, 157, 0.7) !important;
}
.demo-nth-child-nomatch {
  opacity: 0.4;
  filter: grayscale(0.6);
}

.demo-input.demo-focus {
  border-color: var(--primary-color) !important;
  box-shadow: 0 0 0 3px rgba(130, 37, 94, 0.2) !important;
}
.demo-input.demo-focus-active {
  background-color: #e8f4fd !important;
  border-color: #2196f3 !important;
  box-shadow: 0 0 10px rgba(33, 150, 243, 0.3) !important;
}

.demo-item:focus-visible {
  outline: 3px solid var(--accent-color);
  outline-offset: 2px;
  box-shadow: 0 0 0 2px rgba(209, 195, 157, 0.5);
}
.demo-item:focus {
  outline: none;
}

.checkbox-label.demo-style-color {
  color: #e91e63 !important;
  font-weight: 700;
}
.checkbox-label.demo-style-background {
  background: #fce4ec !important;
  padding: 6px 10px;
  border-radius: 6px;
}
.checkbox-label.demo-style-border {
  border: 2px solid #82255e !important;
  padding: 6px 10px;
  border-radius: 6px;
}
.checkbox-label.demo-style-transform {
  transform: scale(1.05);
  display: inline-block;
  font-weight: 700;
}

.demo-input.demo-style-color {
  color: #1565c0 !important;
  border-color: #1565c0 !important;
}
.demo-input.demo-style-background {
  background: #e3f2fd !important;
}
.demo-input.demo-style-border {
  border: 3px solid #82255e !important;
}
.demo-input.demo-style-transform {
  transform: scale(1.02);
  transition: transform 0.2s;
}

.control-group:last-of-type {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.control-group:last-of-type .demo-button {
  display: inline-block;
  width: auto;
  flex: 1 1 auto;
  text-align: center;
  margin-bottom: 0;
}

/* ---------- 15. 伪元素演示 ---------- */
.pseudo-before-icon::before {
  content: "🔹 ";
  color: var(--primary-color);
  font-weight: bold;
  margin-right: 8px;
}
.pseudo-before-quote::before {
  content: "「";
  color: var(--primary-color);
  font-size: 2em;
  font-weight: bold;
  margin-right: 5px;
  line-height: 1;
}
.pseudo-before-highlight::before {
  content: "";
  position: absolute;
  left: -5px;
  top: 0;
  width: 5px;
  height: 100%;
  background-color: var(--primary-color);
  border-radius: 2px;
}
.pseudo-before-border::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  border: 2px dashed var(--primary-color);
  border-radius: 5px;
  box-sizing: border-box;
}

.pseudo-after-icon::after {
  content: " 🔹";
  color: var(--primary-color);
  font-weight: bold;
  margin-left: 8px;
}
.pseudo-after-quote::after {
  content: "」";
  color: var(--primary-color);
  font-size: 2em;
  font-weight: bold;
  margin-left: 5px;
  line-height: 1;
}
.pseudo-after-highlight::after {
  content: "";
  position: absolute;
  right: -5px;
  top: 0;
  width: 5px;
  height: 100%;
  background-color: var(--secondary-color);
  border-radius: 2px;
}
.pseudo-after-border::after {
  content: "";
  position: absolute;
  left: 5px;
  top: 5px;
  width: calc(100% - 10px);
  height: calc(100% - 10px);
  border: 1px solid var(--secondary-color);
  border-radius: 3px;
  box-sizing: border-box;
}

.pseudo-first-letter-icon::first-letter {
  font-size: 2em;
  color: var(--primary-color);
  font-weight: bold;
  float: left;
  line-height: 1;
  margin-right: 5px;
}
.pseudo-first-letter-quote::first-letter {
  font-size: 3em;
  color: var(--primary-color);
  font-weight: bold;
  float: left;
  line-height: 0.8;
  margin-right: 8px;
  font-family: serif;
}
.pseudo-first-letter-highlight::first-letter {
  background-color: var(--primary-color);
  color: white;
  padding: 5px 8px;
  border-radius: 4px;
  font-weight: bold;
  margin-right: 8px;
}
.pseudo-first-letter-border::first-letter {
  border: 2px solid var(--primary-color);
  padding: 5px 8px;
  border-radius: 4px;
  font-weight: bold;
  margin-right: 8px;
  background-color: rgba(130, 37, 94, 0.1);
}

.pseudo-first-line-icon::first-line {
  font-weight: bold;
  color: var(--primary-color);
  letter-spacing: 1px;
}
.pseudo-first-line-quote::first-line {
  font-style: italic;
  color: var(--secondary-color);
  text-decoration: underline;
}
.pseudo-first-line-highlight::first-line {
  background-color: rgba(184, 59, 106, 0.2);
  padding: 2px 5px;
  border-radius: 3px;
}
.pseudo-first-line-border::first-line {
  border-bottom: 2px solid var(--primary-color);
  padding-bottom: 2px;
}

#pseudoElementDemo {
  position: relative;
  padding: 2rem;
  background: white;
  border-radius: var(--border-radius);
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  transition: all 0.3s ease;
  min-height: 200px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 2px solid transparent;
}

#pseudoElementDemo.active {
  border-color: var(--primary-color);
  background: rgba(130, 37, 94, 0.05);
}

#demoText {
  line-height: 1.8;
  text-align: justify;
  margin: 0;
  transition: all 0.3s ease;
  position: relative;
  z-index: 2;
}

.pseudo-effect-preview {
  margin-top: 1rem;
  padding: 1rem;
  background: var(--gray-light);
  border-radius: var(--border-radius);
  border-left: 4px solid var(--primary-color);
}

.pseudo-effect-preview h5 {
  color: var(--primary-color);
  margin-bottom: 0.5rem;
  font-size: 0.9rem;
}

@media (max-width: 768px) {
  #pseudoElementDemo {
    padding: 1.5rem;
    min-height: 180px;
  }

  #demoText {
    font-size: 0.95rem;
    line-height: 1.7;
  }

  .demo-controls-grid {
    grid-template-columns: 1fr !important;
    gap: 1.2rem !important;
  }

  .control-group:last-of-type {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
  }

  .control-group:last-of-type .demo-button {
    flex: 1 1 calc(50% - 0.75rem);
    min-width: 120px;
    margin-bottom: 0;
    padding: 0.75rem 1rem;
    font-size: 0.95rem;
    text-align: center;
  }

  @media (max-width: 480px) {
    .control-group:last-of-type .demo-button {
      flex: 1 1 100%;
    }
  }
}

#demoText {
  position: relative;
}

/* ---------- 16. 高级CSS（滤镜、混合、裁剪、遮罩等） ---------- */
.advanced-demo-element {
  width: 200px;
  height: 200px;
  background: linear-gradient(
    135deg,
    var(--primary-color),
    var(--secondary-color)
  );
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: bold;
  border-radius: 12px;
  transition: all 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  position: relative;
  overflow: hidden;
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
  border: 3px solid rgba(255, 255, 255, 0.1);
}

.advanced-demo-element::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--accent-color), transparent);
}

.advanced-demo-element:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 35px rgba(0, 0, 0, 0.3);
}

.effect-filter {
  filter: blur(5px) brightness(1.2) hue-rotate(45deg);
}
.effect-filter-high {
  filter: blur(10px) brightness(1.5) hue-rotate(180deg) saturate(2);
}
.effect-blend {
  background:
    linear-gradient(45deg, var(--primary-color), var(--secondary-color)),
    repeating-linear-gradient(
      45deg,
      transparent,
      transparent 10px,
      rgba(255, 255, 255, 0.1) 10px,
      rgba(255, 255, 255, 0.1) 20px
    );
  background-blend-mode: overlay;
}
.effect-blend-high {
  background:
    radial-gradient(circle at 30% 30%, var(--accent-color), transparent 50%),
    linear-gradient(45deg, var(--primary-color), var(--secondary-color));
  background-blend-mode: difference;
}
.effect-clip {
  clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%);
}
.effect-clip-high {
  clip-path: polygon(50% 0%, 100% 38%, 82% 100%, 18% 100%, 0% 38%);
}
.effect-gradient {
  background: radial-gradient(
    circle at 30% 30%,
    var(--primary-color),
    var(--secondary-color)
  );
}
.effect-gradient-high {
  background:
    radial-gradient(circle at 20% 20%, var(--accent-color), transparent 40%),
    radial-gradient(circle at 80% 80%, var(--secondary-color), transparent 40%),
    radial-gradient(circle at 50% 50%, var(--primary-color), #2a101b);
}
.effect-mask {
  mask-image: linear-gradient(45deg, black 40%, transparent 60%);
  -webkit-mask-image: linear-gradient(45deg, black 40%, transparent 60%);
}
.effect-mask-high {
  mask-image:
    radial-gradient(circle at center, black 30%, transparent 70%),
    linear-gradient(
      to right,
      transparent 20%,
      black 40%,
      black 60%,
      transparent 80%
    );
  -webkit-mask-image:
    radial-gradient(circle at center, black 30%, transparent 70%),
    linear-gradient(
      to right,
      transparent 20%,
      black 40%,
      black 60%,
      transparent 80%
    );
}
.effect-shadow {
  box-shadow:
    0 0 20px rgba(130, 37, 94, 0.5),
    inset 0 0 20px rgba(255, 255, 255, 0.1);
}
.effect-shadow-high {
  box-shadow:
    0 0 40px rgba(130, 37, 94, 0.8),
    0 0 80px rgba(184, 59, 106, 0.4),
    inset 0 0 30px rgba(255, 255, 255, 0.2);
  filter: drop-shadow(0 0 10px rgba(209, 195, 157, 0.5));
}

/* ---------- 辅助交互：反馈消息与滚动进度 ---------- */
.demo-feedback {
  position: fixed;
  top: 20px;
  right: 20px;
  padding: 12px 20px;
  border-radius: var(--border-radius);
  color: white;
  font-weight: 500;
  z-index: 1000;
  transform: translateX(120%);
  transition: transform 0.3s ease;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.demo-feedback.show {
  transform: translateX(0);
}

.feedback-success {
  background-color: #28a745;
}
.feedback-info {
  background-color: #17a2b8;
}
.feedback-warning {
  background-color: #ffc107;
  color: var(--dark-color);
}

.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 0%;
  height: 3px;
  background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
  z-index: 1000;
  transition: width 0.1s ease;
  pointer-events: none;
}

/* ---------- 表单验证 ---------- */
.field-error {
  color: #f44336;
  font-size: 0.8rem;
  margin-top: 0.25rem;
}

.form-group input.error,
.form-group select.error,
.form-group textarea.error {
  border-color: #f44336;
}

.required {
  color: #f44336;
}

/* ---------- 搜索相关 ---------- */
.search-loading {
  padding: 15px;
  text-align: center;
  color: var(--dark-color);
}

.search-stats {
  padding: 8px 15px;
  background-color: var(--gray-light);
  font-size: 0.8rem;
  color: var(--dark-color);
  border-bottom: 1px solid var(--gray-medium);
}

.search-history-item,
.search-popular-item {
  padding: 10px 15px;
  border-bottom: 1px solid var(--gray-light);
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  gap: 8px;
}

.search-history-item:hover,
.search-popular-item:hover {
  background-color: var(--gray-light);
}

.search-history-icon {
  margin-right: 8px;
  color: var(--primary-color);
}

.search-popular-count {
  background-color: var(--primary-color);
  color: white;
  border-radius: 50%;
  width: 20px;
  height: 20px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  margin-right: 8px;
}

.search-history-remove {
  margin-left: auto;
  background: none;
  border: none;
  color: #999;
  cursor: pointer;
  font-size: 1.2rem;
  padding: 0;
  width: 20px;
  height: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.search-history-remove:hover {
  color: #f44336;
}

.search-result-more {
  padding: 10px 15px;
  text-align: center;
  font-size: 0.9rem;
  color: var(--dark-color);
  border-top: 1px solid var(--gray-light);
}

.show-all-results {
  color: var(--primary-color);
  text-decoration: none;
}

.show-all-results:hover {
  text-decoration: underline;
}

.touch-active {
  background-color: var(--gray-light) !important;
}

/* ===== 6. 响应式设计（全局布局） ===== */
@media (min-width: 576px) {
  .container {
    max-width: 540px;
    padding: 0 15px;
  }
  header {
    padding: 1.75rem 1rem;
  }
  header h1 {
    font-size: 2rem;
  }
  header p {
    font-size: 1.05rem;
  }
  main {
    padding: 1.75rem 1rem;
  }
  .hero-content {
    padding: 2.5rem;
  }
  .hero-content h2 {
    font-size: 2rem;
  }
  .path-step {
    padding: 2rem;
  }
  .featured-card {
    padding: 2rem;
  }
  .quick-link {
    padding: 1.25rem;
  }
  .content-section {
    padding: 1.75rem;
  }
  footer {
    padding: 1.5rem 1rem;
  }
}

@media (min-width: 768px) {
  .container {
    max-width: 720px;
  }
  header {
    padding: 2rem 1rem;
  }
  header h1 {
    font-size: 2.25rem;
  }
  header p {
    font-size: 1.1rem;
  }
  main {
    padding: 2rem 1rem;
  }
  .hero-section {
    flex-direction: row;
    align-items: center;
  }
  .hero-content {
    flex: 1;
    /* 允许收缩：flex 子项默认 min-width:auto，会被内部长代码行撑住而不肯变窄 */
    min-width: 0;
    text-align: left;
  }
  .hero-stats {
    justify-content: flex-start;
  }
  .hero-visual {
    flex: 1;
    /* 关键修复：不加 min-width:0 时，代码卡的最小内容宽度会让本项无法收缩，在 768~991px 溢出主内容区 */
    min-width: 0;
    justify-content: flex-end;
  }
  .path-steps {
    flex-direction: row;
    flex-wrap: wrap;
  }
  .path-step {
    flex: 1;
    min-width: 200px;
  }
  .cards-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  .links-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  .content-section {
    padding: 2rem;
  }
  .tag-list {
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  }
  .form-grid {
    grid-template-columns: 1fr 1fr;
  }
  .demo-content {
    flex-direction: column;
  }
  .layout-grid .demo-content {
    grid-template-columns: 1fr;
  }
  .layout-float .content-section,
  .layout-float .sidebar-section {
    float: none;
    width: 100%;
    margin-right: 0;
  }
  #transformContainer {
    min-height: 350px;
    padding: 10px;
  }
  .transform-demo-element {
    width: 140px;
    height: 140px;
  }
  .positioning-demo-container {
    height: 400px;
  }
  .position-context-indicator {
    width: 150px;
    height: 100px;
  }
  .static-element,
  .reference-element,
  .overlay-element {
    width: 80px;
    height: 60px;
    font-size: 0.7rem;
  }
  .position-demo-element {
    width: 100px;
    height: 80px;
    font-size: 0.8rem;
  }
  .scroll-content {
    height: 150px;
  }
  .scroll-item {
    padding: 15px;
    height: 60px;
  }
  .flex-demo-enhanced {
    width: 100%;
    min-height: 150px;
    padding: 1rem;
  }
  .flex-item-enhanced {
    min-width: 80px;
    min-height: 60px;
    padding: 0.75rem;
    font-size: 0.8rem;
  }
  .color-info p {
    font-size: 0.8rem;
  }
  .demo-output.enhanced #backgroundDemo {
    padding: 1rem;
    min-height: 150px;
  }
  .transition-demo-element {
    width: 80px;
    height: 80px;
    font-size: 0.8rem;
  }
  .element-properties {
    font-size: 0.6rem;
  }
  .advanced-demo-element {
    width: 150px;
    height: 150px;
  }
  .element-title {
    font-size: 0.9rem;
  }
}

@media (min-width: 992px) {
  .container {
    max-width: 960px;
    padding: 0 15px;
  }
  header {
    padding: 2.5rem 1rem;
  }
  header h1 {
    font-size: 2.5rem;
  }
  main {
    padding: 2.5rem 1rem;
  }
  .hamburger {
    display: none;
  }
  .nav-menu {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    gap: 0;
  }
  .nav-menu a {
    padding: 0.8rem 0.6rem;
    font-size: 0.9rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }
  .hero-content {
    padding: 3rem;
  }
  .hero-content h2 {
    font-size: 2.2rem;
  }
  .path-step {
    padding: 2.5rem 1.5rem;
  }
  .featured-card {
    padding: 2.5rem;
  }
  .quick-link {
    padding: 1.5rem;
  }
  .content-section {
    padding: 2.25rem;
  }
  .links-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

@media (min-width: 1200px) {
  .container {
    max-width: 1140px;
  }
  header h1 {
    font-size: 2.8rem;
  }
  .hero-content h2 {
    font-size: 2.5rem;
  }
  .content-section {
    padding: 2.5rem;
  }
  .nav-menu a {
    padding: 0.8rem 1rem;
  }
}

@media (min-width: 1400px) {
  .container {
    max-width: 1320px;
  }
  header {
    padding: 3rem 1rem;
  }
  .hero-content {
    padding: 4rem;
  }
  .content-section {
    padding: 3rem;
  }
}

@media (max-width: 991px) {
  .hamburger {
    display: flex;
  }
  .nav-menu {
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background-color: var(--dark-color);
    flex-direction: column;
    transform: translateY(-10px);
    opacity: 0;
    visibility: hidden;
    z-index: 99;
    box-shadow: 0 5px 10px rgba(0, 0, 0, 0.2);
    display: flex;
  }
  .nav-menu.active {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }
  .nav-menu li {
    width: 100%;
    text-align: center;
  }
  .nav-menu a {
    padding: 1rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  }
  .hamburger.active {
    transform: translateY(-50%) rotate(90deg);
  }
  /* 移动端表格响应式：包装层 div.syntax-table / div.compatibility-table 保留横向滚动能力 */
  .syntax-table,
  .compatibility-table {
    display: block;
    overflow-x: auto;
  }
  /* 表格元素本身必须保持表格布局：display:block 会让内部网格收缩到内容宽度，
     导致整表右侧留白；恢复表格布局后由外层内容容器负责横向滚动 */
  table.syntax-table,
  table.compatibility-table {
    display: table;
    width: 100%;
  }
  .content-section,
  .reference-section,
  .reference-category {
    overflow-x: auto;
  }
  .tag-list {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .footer-nav-links {
    gap: 1rem;
  }
  .footer-nav-link {
    padding: 0.5rem 0.8rem;
    font-size: 0.9rem;
  }
  .search-result-title {
    font-size: 0.9rem;
  }
  .search-result-desc {
    font-size: 0.8rem;
  }
  .demo-controls {
    grid-template-columns: 1fr;
  }
  .demo-info-bar {
    flex-direction: column;
    gap: 1rem;
  }
  .demo-item {
    width: 80px;
    height: 80px;
    font-size: 0.8rem;
  }
  .control-group {
    padding: 1rem;
  }
  .form-demo-section {
    padding: 1rem;
  }
  .demo-container {
    gap: 10px;
    padding: 15px;
  }
  .demo-item {
    width: 70px;
    height: 70px;
    font-size: 0.75rem;
  }
  .demo-controls-grid {
    grid-template-columns: 1fr;
  }
  #pseudoElementDemo {
    padding: 1rem;
    min-height: 150px;
  }
  #demoText {
    font-size: 0.9rem;
    line-height: 1.6;
  }
}

@media (max-width: 576px) {
  .demo-controls-grid {
    grid-template-columns: 1fr !important;
    gap: 16px !important;
  }
  .control-group {
    padding: 16px 12px !important;
  }
  input[type="range"] {
    height: 12px;
  }
  input[type="range"]::-webkit-slider-thumb {
    width: 28px;
    height: 28px;
  }
  .demo-button {
    padding: 12px 16px;
    font-size: 16px;
    width: 100%;
  }
  .info-item span[id="currentTransform"] {
    max-width: 150px;
  }
  #transformContainer .axis-label-x,
  #transformContainer .axis-label-y,
  #transformContainer .axis-label-z {
    font-size: 10px;
    padding: 1px 4px;
  }
  #transformContainer .z-axis {
    width: 50px;
    height: 50px;
  }
}

@media (max-width: 480px) {
  .transform-demo-element {
    width: 120px;
    height: 120px;
  }
}

/* ===== 7. 可访问性与性能（Accessibility & Performance） ===== */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  .path-step:hover,
  .featured-card:hover,
  .quick-link:hover {
    transform: none;
  }
  .hamburger span {
    transition: none;
  }
}

@media (prefers-contrast: more) {
  :root {
    --primary-color: #000000;
    --secondary-color: #333333;
    --accent-color: #ffffff;
    --dark-color: #000000;
    --light-color: #ffffff;
    --gray-light: #ffffff;
  }
  .path-step,
  .featured-card,
  .quick-link {
    border: 2px solid #000;
  }
}

@media print {
  * {
    background: transparent !important;
    color: black !important;
    box-shadow: none !important;
    text-shadow: none !important;
  }
  .path-step,
  .featured-card,
  .quick-link {
    border: 1px solid #000;
    page-break-inside: avoid;
    margin-bottom: 1rem;
  }
  a[href]:after {
    content: " (" attr(href) ")";
  }
  header,
  footer {
    background: white !important;
    color: black !important;
  }
  .hamburger,
  .nav-menu {
    display: none !important;
  }
  .code-example {
    background: white !important;
    color: black !important;
    border: 1px solid #000;
  }
  .code-content code {
    color: black !important;
  }
}