/* =====================================================
   CSS 样式文件 - 瀑布流卡片布局 + 毛玻璃效果
   版本: 1.0.0
   ===================================================== */

/* =====================================================
   第一部分：CSS 变量定义
   ===================================================== */
:root {
  /* 主色调 */
  --primary-color: #6366f1;
  --primary-light: #818cf8;
  --primary-dark: #4f46e5;
  
  /* 辅助色 */
  --secondary-color: #ec4899;
  --accent-color: #06b6d4;
  
  /* 渐变色 */
  --gradient-primary: linear-gradient(135deg, #6366f1 0%, #ec4899 100%);
  --gradient-secondary: linear-gradient(135deg, #06b6d4 0%, #6366f1 100%);
  --gradient-dark: linear-gradient(180deg, #1e1b4b 0%, #312e81 100%);
  --gradient-text: linear-gradient(135deg, #f472b6 0%, #818cf8 50%, #22d3ee 100%);
  
  /* 毛玻璃效果 */
  --glass-bg: rgba(255, 255, 255, 0.1);
  --glass-border: rgba(255, 255, 255, 0.2);
  --glass-shadow: rgba(0, 0, 0, 0.1);
  
  /* 中性色 */
  --bg-dark: #0f0f23;
  --bg-card: rgba(30, 27, 75, 0.6);
  --text-primary: #ffffff;
  --text-secondary: rgba(255, 255, 255, 0.7);
  --text-muted: rgba(255, 255, 255, 0.5);
  
  /* 间距系统 */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  
  /* 圆角 */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  
  /* 阴影 */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.15);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.2);
  --shadow-glow: 0 0 40px rgba(99, 102, 241, 0.3);
  
  /* 过渡 */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.5s ease;
  
  /* 字体 */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'Fira Code', monospace;
  
  /* 容器宽度 */
  --container-max: 1400px;
  --container-narrow: 800px;
}

/* =====================================================
   第二部分：CSS 重置与基础样式
   ===================================================== */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-family);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--bg-dark);
  min-height: 100vh;
  overflow-x: hidden;
}

/* 背景装饰 */
body::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: 
    radial-gradient(ellipse at 20% 20%, rgba(99, 102, 241, 0.15) 0%, transparent 50%),
    radial-gradient(ellipse at 80% 80%, rgba(236, 72, 153, 0.15) 0%, transparent 50%),
    radial-gradient(ellipse at 50% 50%, rgba(6, 182, 212, 0.1) 0%, transparent 70%);
  pointer-events: none;
  z-index: -1;
}

/* 链接样式 */
a {
  color: var(--primary-light);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--accent-color);
}

/* 列表样式 */
ul, ol {
  list-style: none;
}

/* 图片样式 */
img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* 按钮重置 */
button {
  font-family: inherit;
  font-size: inherit;
  border: none;
  background: none;
  cursor: pointer;
  outline: none;
}

/* 输入框重置 */
input, textarea, select {
  font-family: inherit;
  font-size: inherit;
  border: none;
  outline: none;
  background: transparent;
}

/* =====================================================
   第三部分：容器与布局
   ===================================================== */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

.container--narrow {
  max-width: var(--container-narrow);
}

/* 瀑布流布局 */
.waterfall-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--spacing-lg);
  grid-auto-flow: dense;
}

/* 瀑布流卡片列数响应式 */
@media (max-width: 1200px) {
  .waterfall-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 900px) {
  .waterfall-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 600px) {
  .waterfall-grid {
    grid-template-columns: 1fr;
  }
}

/* 不同高度的瀑布流卡片 */
.waterfall-item {
  break-inside: avoid;
  margin-bottom: var(--spacing-lg);
}

.waterfall-item--tall {
  grid-row: span 2;
}

.waterfall-item--wide {
  grid-column: span 2;
}

.waterfall-item--large {
  grid-row: span 2;
  grid-column: span 2;
}

@media (max-width: 600px) {
  .waterfall-item--wide,
  .waterfall-item--large {
    grid-column: span 1;
    grid-row: span 1;
  }
}

/* 弹性布局工具类 */
.flex {
  display: flex;
}

.flex-col {
  flex-direction: column;
}

.flex-wrap {
  flex-wrap: wrap;
}

.items-center {
  align-items: center;
}

.items-start {
  align-items: flex-start;
}

.items-end {
  align-items: flex-end;
}

.justify-center {
  justify-content: center;
}

.justify-between {
  justify-content: space-between;
}

.justify-end {
  justify-content: flex-end;
}

.gap-sm { gap: var(--spacing-sm); }
.gap-md { gap: var(--spacing-md); }
.gap-lg { gap: var(--spacing-lg); }
.gap-xl { gap: var(--spacing-xl); }

/* =====================================================
   第四部分：导航栏
   ===================================================== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: var(--spacing-md) 0;
  transition: all var(--transition-normal);
}

.navbar--scrolled {
  background: var(--glass-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--glass-border);
  padding: var(--spacing-sm) 0;
}

.navbar__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

.navbar__logo {
  font-size: 1.5rem;
  font-weight: 700;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  transition: transform var(--transition-fast);
}

.navbar__logo:hover {
  transform: scale(1.05);
}

.navbar__menu {
  display: flex;
  align-items: center;
  gap: var(--spacing-xl);
}

.navbar__link {
  position: relative;
  font-weight: 500;
  color: var(--text-secondary);
  padding: var(--spacing-sm) 0;
  transition: color var(--transition-fast);
}

.navbar__link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gradient-primary);
  transition: width var(--transition-normal);
}

.navbar__link:hover {
  color: var(--text-primary);
}

.navbar__link:hover::after {
  width: 100%;
}

.navbar__link--active {
  color: var(--text-primary);
}

.navbar__link--active::after {
  width: 100%;
}

/* 汉堡菜单按钮 */
.navbar__toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: var(--spacing-sm);
}

.navbar__toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: all var(--transition-fast);
}

.navbar__toggle--active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.navbar__toggle--active span:nth-child(2) {
  opacity: 0;
}

.navbar__toggle--active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* 移动端导航 */
@media (max-width: 768px) {
  .navbar__menu {
    position: fixed;
    top: 0;
    right: -100%;
    width: 80%;
    max-width: 300px;
    height: 100vh;
    flex-direction: column;
    justify-content: center;
    gap: var(--spacing-xl);
    background: var(--glass-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-left: 1px solid var(--glass-border);
    transition: right var(--transition-normal);
  }
  
  .navbar__menu--active {
    right: 0;
  }
  
  .navbar__toggle {
    display: flex;
    z-index: 1001;
  }
}

/* =====================================================
   第五部分：卡片组件
   ===================================================== */
.card {
  position: relative;
  background: var(--glass-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: all var(--transition-normal);
}

.card::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,0.1) 0%, transparent 50%);
  pointer-events: none;
}

.card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-lg), var(--shadow-glow);
  border-color: rgba(255, 255, 255, 0.3);
}

.card__image {
  position: relative;
  width: 100%;
  padding-top: 66.67%;
  overflow: hidden;
}

.card__image img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-slow);
}

.card:hover .card__image img {
  transform: scale(1.1);
}

.card__overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, transparent 0%, rgba(0,0,0,0.6) 100%);
  opacity: 0;
  transition: opacity var(--transition-normal);
}

.card:hover .card__overlay {
  opacity: 1;
}

.card__badge {
  position: absolute;
  top: var(--spacing-md);
  left: var(--spacing-md);
  padding: var(--spacing-xs) var(--spacing-sm);
  background: var(--gradient-primary);
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.card__content {
  padding: var(--spacing-lg);
}

.card__category {
  display: inline-block;
  padding: var(--spacing-xs) var(--spacing-sm);
  background: rgba(99, 102, 241, 0.2);
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--primary-light);
  margin-bottom: var(--spacing-sm);
  transition: all var(--transition-fast);
}

.card:hover .card__category {
  background: rgba(99, 102, 241, 0.4);
}

.card__title {
  font-size: 1.25rem;
  font-weight: 700;
  line-height: 1.4;
  margin-bottom: var(--spacing-sm);
  color: var(--text-primary);
  transition: color var(--transition-fast);
}

.card:hover .card__title {
  color: var(--primary-light);
}

.card__description {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: var(--spacing-md);
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.card__footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--spacing-md);
  border-top: 1px solid var(--glass-border);
}

.card__meta {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-size: 0.75rem;
  color: var(--text-muted);
}

.card__avatar {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  object-fit: cover;
  border: 2px solid var(--glass-border);
}

.card__icon {
  width: 20px;
  height: 20px;
  fill: currentColor;
}

/* 卡片尺寸变体 */
.card--sm .card__content {
  padding: var(--spacing-md);
}

.card--sm .card__title {
  font-size: 1rem;
}

.card--lg .card__content {
  padding: var(--spacing-xl);
}

.card--lg .card__title {
  font-size: 1.5rem;
}

/* =====================================================
   第六部分：按钮组件
   ===================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-md) var(--spacing-xl);
  font-weight: 600;
  font-size: 0.875rem;
  border-radius: var(--radius-md);
  transition: all var(--transition-normal);
  cursor: pointer;
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 50%;
  transform: translate(-50%, -50%);
  transition: width 0.6s, height 0.6s;
}

.btn:active::before {
  width: 300px;
  height: 300px;
}

/* 主要按钮 */
.btn--primary {
  background: var(--gradient-primary);
  color: white;
  box-shadow: 0 4px 15px rgba(99, 102, 241, 0.4);
}

.btn--primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(99, 102, 241, 0.6);
}

.btn--primary:active {
  transform: translateY(0);
}

/* 次要按钮 */
.btn--secondary {
  background: var(--glass-bg);
  color: var(--text-primary);
  border: 1px solid var(--glass-border);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.btn--secondary:hover {
  background: rgba(255, 255, 255, 0.2);
  border-color: var(--primary-light);
}

/* 轮廓按钮 */
.btn--outline {
  background: transparent;
  color: var(--primary-light);
  border: 2px solid var(--primary-light);
}

.btn--outline:hover {
  background: var(--primary-light);
  color: white;
}

/* 文字按钮 */
.btn--text {
  background: transparent;
  color: var(--primary-light);
  padding: var(--spacing-sm) var(--spacing-md);
}

.btn--text:hover {
  background: rgba(99, 102, 241, 0.1);
}

/* 按钮尺寸 */
.btn--sm {
  padding: var(--spacing-sm) var(--spacing-md);
  font-size: 0.75rem;
}

.btn--lg {
  padding: var(--spacing-lg) var(--spacing-2xl);
  font-size: 1rem;
}

/* 按钮图标 */
.btn__icon {
  width: 18px;
  height: 18px;
  fill: currentColor;
}

/* 按钮组 */
.btn-group {
  display: flex;
  gap: var(--spacing-md);
  flex-wrap: wrap;
}

/* 渐变文字按钮 */
.btn--gradient-text {
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* =====================================================
   第七部分：表单组件
   ===================================================== */
.form-group {
  margin-bottom: var(--spacing-lg);
}

.form-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: var(--spacing-sm);
}

.form-input {
  width: 100%;
  padding: var(--spacing-md) var(--spacing-lg);
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: 1rem;
  transition: all var(--transition-fast);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.form-input::placeholder {
  color: var(--text-muted);
}

.form-input:focus {
  border-color: var(--primary-light);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.form-input:hover:not(:focus) {
  border-color: rgba(255, 255, 255, 0.3);
}

/* 文本域 */
.form-textarea {
  min-height: 120px;
  resize: vertical;
}

/* 选择框 */
.form-select {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23ffffff' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right var(--spacing-md) center;
  padding-right: var(--spacing-2xl);
}

/* 复选框和单选框 */
.form-check {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  cursor: pointer;
}

.form-check__input {
  appearance: none;
  width: 20px;
  height: 20px;
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  position: relative;
}

.form-check__input:checked {
  background: var(--gradient-primary);
  border-color: transparent;
}

.form-check__input:checked::after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 6px;
  height: 10px;
  border: 2px solid white;
  border-top: none;
  border-left: none;
  transform: translate(-50%, -60%) rotate(45deg);
}

.form-check__input:hover {
  border-color: var(--primary-light);
}

.form-check__input[type="radio"] {
  border-radius: 50%;
}

.form-check__input[type="radio"]:checked::after {
  width: 8px;
  height: 8px;
  background: white;
  border: none;
  border-radius: 50%;
  transform: translate(-50%, -50%);
}

/* 开关 */
.form-switch {
  position: relative;
  width: 48px;
  height: 24px;
}

.form-switch__input {
  opacity: 0;
  width: 0;
  height: 0;
}

.form-switch__slider {
  position: absolute;
  cursor: pointer;
  inset: 0;
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: 24px;
  transition: all var(--transition-normal);
}

.form-switch__slider::before {
  content: '';
  position: absolute;
  height: 18px;
  width: 18px;
  left: 3px;
  bottom: 2px;
  background: white;
  border-radius: 50%;
  transition: all var(--transition-normal);
}

.form-switch__input:checked + .form-switch__slider {
  background: var(--gradient-primary);
  border-color: transparent;
}

.form-switch__input:checked + .form-switch__slider::before {
  transform: translateX(24px);
}

/* 输入组 */
.input-group {
  display: flex;
}

.input-group .form-input {
  border-radius: var(--radius-md) 0 0 var(--radius-md);
}

.input-group .btn {
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

/* =====================================================
   第八部分：标题与排版
   ===================================================== */
.section {
  padding: var(--spacing-2xl) 0;
}

.section--lg {
  padding: 100px 0;
}

.section__header {
  text-align: center;
  margin-bottom: var(--spacing-2xl);
}

.section__badge {
  display: inline-block;
  padding: var(--spacing-xs) var(--spacing-md);
  background: rgba(99, 102, 241, 0.2);
  border-radius: var(--radius-xl);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--primary-light);
  margin-bottom: var(--spacing-md);
}

.section__title {
  font-size: 3rem;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: var(--spacing-md);
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.section__subtitle {
  font-size: 1.125rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

@media (max-width: 768px) {
  .section__title {
    font-size: 2rem;
  }
  
  .section__subtitle {
    font-size: 1rem;
  }
}

/* 大号粗体标题 */
.heading-xl {
  font-size: 4rem;
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: -0.02em;
}

.heading-lg {
  font-size: 2.5rem;
  font-weight: 700;
  line-height: 1.2;
}

.heading-md {
  font-size: 1.5rem;
  font-weight: 600;
  line-height: 1.3;
}

.heading-sm {
  font-size: 1.125rem;
  font-weight: 600;
}

@media (max-width: 768px) {
  .heading-xl {
    font-size: 2.5rem;
  }
  
  .heading-lg {
    font-size: 1.75rem;
  }
}

/* 渐变文字 */
.text-gradient {
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* 段落 */
.text-lead {
  font-size: 1.25rem;
  color: var(--text-secondary);
  line-height: 1.8;
}

.text-muted {
  color: var(--text-muted);
}

.text-center {
  text-align: center;
}

/* =====================================================
   第九部分：装饰元素
   ===================================================== */

/* 几何装饰 */
.decor-circle {
  position: absolute;
  border-radius: 50%;
  background: var(--gradient-primary);
  opacity: 0.1;
  pointer-events: none;
}

.decor-circle--lg {
  width: 400px;
  height: 400px;
}

.decor-circle--md {
  width: 200px;
  height: 200px;
}

.decor-circle--sm {
  width: 100px;
  height: 100px;
}

/* 浮动动画 */
@keyframes float {
  0%, 100% {
    transform: translateY(0) rotate(0deg);
  }
  50% {
    transform: translateY(-20px) rotate(5deg);
  }
}

.float-animation {
  animation: float 6s ease-in-out infinite;
}

/* 脉冲动画 */
@keyframes pulse {
  0%, 100% {
    opacity: 0.1;
    transform: scale(1);
  }
  50% {
    opacity: 0.2;
    transform: scale(1.1);
  }
}

.pulse-animation {
  animation: pulse 4s ease-in-out infinite;
}

/* 发光效果 */
.glow {
  box-shadow: var(--shadow-glow);
}

/* 光晕装饰 */
.glow-orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(60px);
  pointer-events: none;
}

.glow-orb--primary {
  background: var(--primary-color);
  opacity: 0.3;
}

.glow-orb--secondary {
  background: var(--secondary-color);
  opacity: 0.3;
}

.glow-orb--accent {
  background: var(--accent-color);
  opacity: 0.3;
}

/* 边框装饰 */
.border-gradient {
  position: relative;
}

.border-gradient::before {
  content: '';
  position: absolute;
  inset: -2px;
  background: var(--gradient-primary);
  border-radius: inherit;
  z-index: -1;
  opacity: 0;
  transition: opacity var(--transition-normal);
}

.border-gradient:hover::before {
  opacity: 1;
}

/* 网格背景装饰 */
.grid-pattern {
  position: absolute;
  inset: 0;
  background-image: 
    linear-gradient(rgba(255,255,255,0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.03) 1px, transparent 1px);
  background-size: 50px 50px;
  pointer-events: none;
}

/* =====================================================
   第十部分：页脚
   ===================================================== */
.footer {
  position: relative;
  padding: var(--spacing-2xl) 0;
  background: var(--glass-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-top: 1px solid var(--glass-border);
}

.footer__inner {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--spacing-2xl);
}

@media (max-width: 900px) {
  .footer__inner {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 600px) {
  .footer__inner {
    grid-template-columns: 1fr;
    text-align: center;
  }
}

.footer__brand {
  max-width: 300px;
}

.footer__logo {
  font-size: 1.5rem;
  font-weight: 700;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: var(--spacing-md);
}

.footer__description {
  color: var(--text-muted);
  font-size: 0.875rem;
  line-height: 1.6;
}

.footer__title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: var(--spacing-lg);
  color: var(--text-primary);
}

.footer__links {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.footer__link {
  color: var(--text-muted);
  font-size: 0.875rem;
  transition: color var(--transition-fast);
}

.footer__link:hover {
  color: var(--primary-light);
}

.footer__social {
  display: flex;
  gap: var(--spacing-md);
}

@media (max-width: 600px) {
  .footer__social {
    justify-content: center;
  }
}

.footer__social-link {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.footer__social-link:hover {
  background: var(--gradient-primary);
  border-color: transparent;
  color: white;
  transform: translateY(-3px);
}

.footer__bottom {
  margin-top: var(--spacing-2xl);
  padding-top: var(--spacing-lg);
  border-top: 1px solid var(--glass-border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--spacing-md);
}

@media (max-width: 600px) {
  .footer__bottom {
    flex-direction: column;
    text-align: center;
  }
}

.footer__copyright {
  color: var(--text-muted);
  font-size: 0.875rem;
}

.footer__legal {
  display: flex;
  gap: var(--spacing-lg);
}

/* =====================================================
   第十一部分：工具类与辅助类
   ===================================================== */

/* 间距 */
.m-0 { margin: 0; }
.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }
.mt-2xl { margin-top: var(--spacing-2xl); }

.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.mb-xl { margin-bottom: var(--spacing-xl); }
.mb-2xl { margin-bottom: var(--spacing-2xl); }

/* 显示 */
.hidden { display: none; }
.block { display: block; }
.inline-block { display: inline-block; }

@media (max-width: 768px) {
  .hidden-md { display: none; }
}

@media (min-width: 769px) {
  .show-md { display: none; }
}

/* 定位 */
.relative { position: relative; }
.absolute { position: absolute; }
.fixed { position: fixed; }
.sticky { position: sticky; }

/* 层级 */
.z-10 { z-index: 10; }
.z-20 { z-index: 20; }
.z-50 { z-index: 50; }
.z-100 { z-index: 100; }

/* 溢出 */
.overflow-hidden { overflow: hidden; }
.overflow-auto { overflow: auto; }

/* 圆角 */
.rounded-sm { border-radius: var(--radius-sm); }
.rounded-md { border-radius: var(--radius-md); }
.rounded-lg { border-radius: var(--radius-lg); }
.rounded-full { border-radius: 9999px; }

/* 宽度 */
.w-full { width: 100%; }
.max-w-sm { max-width: 24rem; }
.max-w-md { max-width: 28rem; }
.max-w-lg { max-width: 32rem; }
.max-w-xl { max-width: 36rem; }

/* 伪元素分隔线 */
.divider {
  height: 1px;
  background: var(--glass-border);
  margin: var(--spacing-xl) 0;
}

/* 加载动画 */
@keyframes spin {
  to { transform: rotate(360deg); }
}

.loader {
  width: 40px;
  height: 40px;
  border: 3px solid var(--glass-border);
  border-top-color: var(--primary-light);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

/* 骨架屏 */
.skeleton {
  background: linear-gradient(
    90deg,
    var(--glass-bg) 25%,
    rgba(255,255,255,0.1) 50%,
    var(--glass-bg) 75%
  );
  background-size: 200% 100%;
  animation: skeleton-loading 1.5s infinite;
}

@keyframes skeleton-loading {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

/* =====================================================
   第十二部分：响应式媒体查询
   ===================================================== */

/* 平板设备 */
@media (max-width: 1024px) {
  :root {
    --spacing-2xl: 2rem;
  }
  
  .section--lg {
    padding: 80px 0;
  }
}

/* 移动设备 */
@media (max-width: 768px) {
  :root {
    font-size: 14px;
  }
  
  .container {
    padding: 0 var(--spacing-md);
  }
  
  .section {
    padding: var(--spacing-xl) 0;
  }
  
  .section--lg {
    padding: 60px 0;
  }
}

/* 小屏手机 */
@media (max-width: 480px) {
  .btn {
    width: 100%;
  }
  
  .btn-group {
    flex-direction: column;
  }
}

/* =====================================================
   第十三部分：动画关键帧
   ===================================================== */

/* 淡入上移动画 */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.animate-fade-in-up {
  animation: fadeInUp 0.6s ease forwards;
}

/* 缩放淡入动画 */
@keyframes fadeInScale {
  from {
    opacity: 0;
    transform: scale(0.9);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

.animate-fade-in-scale {
  animation: fadeInScale 0.4s ease forwards;
}

/* 滑入动画 */
@keyframes slideInLeft {
  from {
    opacity: 0;
    transform: translateX(-30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.animate-slide-in-left {
  animation: slideInLeft 0.5s ease forwards;
}

@keyframes slideInRight {
  from {
    opacity: 0;
    transform: translateX(30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.animate-slide-in-right {
  animation: slideInRight 0.5s ease forwards;
}

/* 延迟类 */
.delay-100 { animation-delay: 0.1s; }
.delay-200 { animation-delay: 0.2s; }
.delay-300 { animation-delay: 0.3s; }
.delay-400 { animation-delay: 0.4s; }
.delay-500 { animation-delay: 0.5s; }

/* =====================================================
   第十四部分：滚动条美化
   ===================================================== */

::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: rgba(255, 255, 255, 0.05);
}

::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.2);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: rgba(255, 255, 255, 0.3);
}

/* Firefox 滚动条 */
* {
  scrollbar-width: thin;
  scrollbar-color: rgba(255, 255, 255, 0.2) rgba(255, 255, 255, 0.05);
}

/* =====================================================
   第十五部分：选中样式
   ===================================================== */

::selection {
  background: rgba(99, 102, 241, 0.4);
  color: white;
}

::-moz-selection {
  background: rgba(99, 102, 241, 0.4);
  color: white;
}

/* =====================================================
   第十六部分：无障碍支持
   ===================================================== */

/* 焦点可见样式 */
:focus-visible {
  outline: 2px solid var(--primary-light);
  outline-offset: 2px;
}

/* 减少动画偏好 */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* 高对比度模式 */
@media (prefers-contrast: high) {
  :root {
    --glass-bg: rgba(0, 0, 0, 0.8);
    --glass-border: rgba(255, 255, 255, 0.5);
  }
}
```