/* ========================================
   合肥枢维智能科技有限公司 - 全局样式
   现代化科技创新企业官网
   ======================================== */

/* CSS 变量定义 */
:root {
  /* 主色调 - 紫色渐变科技感 */
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --primary-light: #818cf8;
  --secondary: #8b5cf6;
  --accent: #d946ef;

  /* 中性色 */
  --slate-50: #f8fafc;
  --slate-100: #f1f5f9;
  --slate-200: #e2e8f0;
  --slate-300: #cbd5e1;
  --slate-400: #94a3b8;
  --slate-500: #64748b;
  --slate-600: #475569;
  --slate-700: #334155;
  --slate-800: #1e293b;
  --slate-900: #0f172a;

  /* 功能色 */
  --success: #10b981;
  --warning: #f59e0b;
  --error: #ef4444;

  /* 渐变 */
  --gradient-primary: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #d946ef 100%);
  --gradient-dark: linear-gradient(135deg, #1e293b 0%, #0f172a 100%);

  /* 阴影 */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
  --shadow-glow: 0 0 40px rgba(99, 102, 241, 0.3);

  /* 圆角 */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  --radius-full: 9999px;

  /* 过渡 */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 300ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* 重置样式 */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--slate-800);
  background-color: #ffffff;
  overflow-x: hidden;
}

/* 容器 */
.container {
  width: 100%;
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.container-narrow {
  max-width: 960px;
}

.container-wide {
  max-width: 1440px;
}

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

a:hover {
  color: var(--primary-dark);
}

/* 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  font-size: 1rem;
  font-weight: 500;
  border-radius: var(--radius-lg);
  border: none;
  cursor: pointer;
  transition: all var(--transition-base);
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--gradient-primary);
  color: white;
  box-shadow: var(--shadow-md), 0 0 20px rgba(99, 102, 241, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg), 0 0 30px rgba(99, 102, 241, 0.4);
  color: white;
}

.btn-secondary {
  background: white;
  color: var(--primary);
  border: 2px solid var(--primary);
}

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

.btn-outline {
  background: transparent;
  color: var(--slate-700);
  border: 2px solid var(--slate-300);
}

.btn-outline:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.btn-lg {
  padding: 1rem 2rem;
  font-size: 1.125rem;
}

.btn-sm {
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
}

/* 标题样式 */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  color: var(--slate-900);
}

h1 { font-size: clamp(2rem, 5vw, 3.5rem); }
h2 { font-size: clamp(1.75rem, 4vw, 2.5rem); }
h3 { font-size: clamp(1.25rem, 3vw, 1.75rem); }
h4 { font-size: clamp(1.125rem, 2vw, 1.25rem); }

/* 段落 */
p {
  margin-bottom: 1rem;
}

.lead {
  font-size: 1.25rem;
  color: var(--slate-600);
  line-height: 1.8;
}

/* 导航栏 */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--slate-200);
  transition: all var(--transition-base);
}

.navbar.scrolled {
  box-shadow: var(--shadow-md);
}

.navbar-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.5rem;
  max-width: 1280px;
  margin: 0 auto;
}

.navbar-brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--slate-900);
}

.navbar-brand img {
  height: 40px;
  width: auto;
}

.navbar-brand span {
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.navbar-menu {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  list-style: none;
}

.navbar-menu a {
  display: block;
  padding: 0.5rem 1rem;
  color: var(--slate-600);
  font-weight: 500;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
}

.navbar-menu a:hover,
.navbar-menu a.active {
  color: var(--primary);
  background: rgba(99, 102, 241, 0.1);
}

.navbar-toggle {
  display: none;
  flex-direction: column;
  gap: 4px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
}

.navbar-toggle span {
  width: 24px;
  height: 2px;
  background: var(--slate-700);
  border-radius: 2px;
  transition: all var(--transition-fast);
}

/* 页脚 */
.footer {
  background: var(--slate-900);
  color: var(--slate-300);
  padding: 4rem 0 2rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr repeat(3, 1fr);
  gap: 3rem;
  margin-bottom: 3rem;
}

.footer-brand {
  max-width: 300px;
}

.footer-brand img {
  height: 50px;
  margin-bottom: 1rem;
}

.footer-brand p {
  font-size: 0.875rem;
  line-height: 1.8;
}

.footer-title {
  font-size: 1rem;
  font-weight: 600;
  color: white;
  margin-bottom: 1rem;
}

.footer-links {
  list-style: none;
}

.footer-links li {
  margin-bottom: 0.5rem;
}

.footer-links a {
  color: var(--slate-400);
  font-size: 0.875rem;
  transition: color var(--transition-fast);
}

.footer-links a:hover {
  color: var(--primary-light);
}

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 2rem;
  border-top: 1px solid var(--slate-800);
  font-size: 0.875rem;
  color: var(--slate-500);
}

.footer-social {
  display: flex;
  gap: 1rem;
}

.footer-social a {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-full);
  background: var(--slate-800);
  color: var(--slate-400);
  transition: all var(--transition-fast);
}

.footer-social a:hover {
  background: var(--primary);
  color: white;
}

/* 通用区块样式 */
.section {
  padding: 6rem 0;
}

.section-sm {
  padding: 4rem 0;
}

.section-lg {
  padding: 8rem 0;
}

.section-header {
  text-align: center;
  max-width: 800px;
  margin: 0 auto 4rem;
}

.section-label {
  display: inline-block;
  padding: 0.5rem 1rem;
  background: rgba(99, 102, 241, 0.1);
  color: var(--primary);
  font-size: 0.875rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  margin-bottom: 1rem;
}

.section-title {
  margin-bottom: 1rem;
}

.section-desc {
  color: var(--slate-600);
  font-size: 1.125rem;
}

/* 卡片样式 */
.card {
  background: white;
  border-radius: var(--radius-xl);
  padding: 2rem;
  box-shadow: var(--shadow-md);
  border: 1px solid var(--slate-200);
  transition: all var(--transition-base);
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-xl);
  border-color: var(--primary-light);
}

.card-icon {
  width: 60px;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-lg);
  margin-bottom: 1.5rem;
}

.card-icon.gradient {
  background: var(--gradient-primary);
  color: white;
}

.card-icon.light {
  background: rgba(99, 102, 241, 0.1);
  color: var(--primary);
}

.card-title {
  font-size: 1.25rem;
  margin-bottom: 0.75rem;
}

.card-desc {
  color: var(--slate-600);
  font-size: 0.9375rem;
  line-height: 1.7;
}

/* 网格布局 */
.grid {
  display: grid;
  gap: 2rem;
}

.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

/* Hero 区块 */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding-top: 80px;
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 50%, #e2e8f0 100%);
  z-index: -2;
}

.hero-shapes {
  position: absolute;
  inset: 0;
  z-index: -1;
  overflow: hidden;
}

.hero-shapes .shape {
  position: absolute;
  border-radius: 50%;
  background: var(--gradient-primary);
  opacity: 0.1;
  filter: blur(60px);
}

.hero-shapes .shape-1 {
  width: 600px;
  height: 600px;
  top: -200px;
  right: -100px;
}

.hero-shapes .shape-2 {
  width: 400px;
  height: 400px;
  bottom: -100px;
  left: -100px;
}

.hero-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
}

.hero-text {
  max-width: 600px;
}

.hero-label {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 1rem;
  background: rgba(99, 102, 241, 0.1);
  color: var(--primary);
  font-size: 0.875rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  margin-bottom: 1.5rem;
}

.hero-title {
  margin-bottom: 1.5rem;
  line-height: 1.1;
}

.hero-title .highlight {
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-desc {
  font-size: 1.25rem;
  color: var(--slate-600);
  margin-bottom: 2rem;
  line-height: 1.8;
}

.hero-buttons {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.hero-image {
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
}

.hero-visual {
  width: 100%;
  max-width: 500px;
  aspect-ratio: 1;
  background: var(--gradient-primary);
  border-radius: var(--radius-2xl);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-glow);
}

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

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

@keyframes gradient {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

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

.animate-pulse {
  animation: pulse 2s ease-in-out infinite;
}

.animate-gradient {
  background-size: 200% 200%;
  animation: gradient 3s ease infinite;
}

/* 统计数据 */
.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 2rem;
  padding: 3rem;
  background: white;
  border-radius: var(--radius-2xl);
  box-shadow: var(--shadow-lg);
}

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

.stat-value {
  font-size: 3rem;
  font-weight: 700;
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
  margin-bottom: 0.5rem;
}

.stat-label {
  color: var(--slate-600);
  font-size: 0.9375rem;
}

/* 特性列表 */
.feature-list {
  list-style: none;
}

.feature-list li {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 0;
  color: var(--slate-700);
}

.feature-list svg {
  width: 20px;
  height: 20px;
  color: var(--success);
  flex-shrink: 0;
}

/* 表单样式 */
.form-group {
  margin-bottom: 1.5rem;
}

.form-label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 500;
  color: var(--slate-700);
}

.form-input,
.form-textarea,
.form-select {
  width: 100%;
  padding: 0.875rem 1rem;
  font-size: 1rem;
  border: 2px solid var(--slate-200);
  border-radius: var(--radius-lg);
  transition: all var(--transition-fast);
  font-family: inherit;
}

.form-input:focus,
.form-textarea:focus,
.form-select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

.form-textarea {
  min-height: 150px;
  resize: vertical;
}

/* 页面标题区块 */
.page-header {
  position: relative;
  padding: 10rem 0 5rem;
  background: var(--gradient-dark);
  overflow: hidden;
}

.page-header::before {
  content: '';
  position: absolute;
  inset: 0;
  background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%236366f1' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
  opacity: 0.5;
}

.page-header-content {
  position: relative;
  text-align: center;
  max-width: 800px;
  margin: 0 auto;
}

.page-header h1 {
  color: white;
  margin-bottom: 1rem;
}

.page-header p {
  color: var(--slate-300);
  font-size: 1.25rem;
}

/* Breadcrumb */
.breadcrumb {
  display: flex;
  justify-content: center;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
  font-size: 0.875rem;
}

.breadcrumb a {
  color: var(--slate-400);
}

.breadcrumb a:hover {
  color: white;
}

.breadcrumb .separator {
  color: var(--slate-600);
}

.breadcrumb .current {
  color: var(--primary-light);
}

/* 时间线 */
.timeline {
  position: relative;
  max-width: 800px;
  margin: 0 auto;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  width: 2px;
  height: 100%;
  background: var(--slate-200);
}

.timeline-item {
  display: flex;
  justify-content: flex-end;
  padding-bottom: 3rem;
  position: relative;
}

.timeline-item:nth-child(even) {
  justify-content: flex-start;
}

.timeline-content {
  width: calc(50% - 40px);
  padding: 1.5rem;
  background: white;
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-md);
}

.timeline-item:nth-child(even) .timeline-content {
  margin-left: auto;
}

.timeline-dot {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  width: 20px;
  height: 20px;
  background: var(--gradient-primary);
  border-radius: 50%;
  border: 4px solid white;
  box-shadow: var(--shadow-md);
}

.timeline-date {
  font-size: 0.875rem;
  color: var(--primary);
  font-weight: 600;
  margin-bottom: 0.5rem;
}

/* 团队成员卡片 */
.team-card {
  text-align: center;
}

.team-avatar {
  width: 150px;
  height: 150px;
  border-radius: 50%;
  margin: 0 auto 1.5rem;
  background: var(--gradient-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
  color: white;
  font-weight: 700;
}

.team-name {
  font-size: 1.25rem;
  margin-bottom: 0.25rem;
}

.team-role {
  color: var(--primary);
  font-weight: 500;
  margin-bottom: 1rem;
}

.team-bio {
  color: var(--slate-600);
  font-size: 0.9375rem;
}

/* 新闻卡片 */
.news-card {
  overflow: hidden;
}

.news-image {
  width: 100%;
  height: 200px;
  object-fit: cover;
  margin: -2rem -2rem 1.5rem;
  border-radius: 0;
}

.news-meta {
  display: flex;
  gap: 1rem;
  font-size: 0.875rem;
  color: var(--slate-500);
  margin-bottom: 0.75rem;
}

.news-tag {
  color: var(--primary);
  font-weight: 500;
}

/* 案例研究 */
.case-study {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
  margin-bottom: 4rem;
}

.case-study.reverse {
  direction: rtl;
}

.case-study.reverse > * {
  direction: ltr;
}

.case-image {
  border-radius: var(--radius-2xl);
  overflow: hidden;
  box-shadow: var(--shadow-xl);
}

.case-image img {
  width: 100%;
  height: 400px;
  object-fit: cover;
}

.case-content h3 {
  margin-bottom: 1rem;
}

.case-content p {
  color: var(--slate-600);
  margin-bottom: 1.5rem;
}

.case-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}

.case-tag {
  padding: 0.25rem 0.75rem;
  background: rgba(99, 102, 241, 0.1);
  color: var(--primary);
  font-size: 0.875rem;
  border-radius: var(--radius-full);
}

/* 技术栈展示 */
.tech-stack {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: center;
}

.tech-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  padding: 1.5rem;
  background: white;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  min-width: 100px;
  transition: all var(--transition-base);
}

.tech-item:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.tech-icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.tech-icon img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.tech-name {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--slate-700);
}

/* 联系信息 */
.contact-info {
  display: grid;
  gap: 2rem;
}

.contact-item {
  display: flex;
  gap: 1rem;
  align-items: flex-start;
}

.contact-icon {
  width: 50px;
  height: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(99, 102, 241, 0.1);
  color: var(--primary);
  border-radius: var(--radius-lg);
  flex-shrink: 0;
}

.contact-text h4 {
  font-size: 1rem;
  margin-bottom: 0.25rem;
}

.contact-text p {
  color: var(--slate-600);
  font-size: 0.9375rem;
}

/* 地图容器 */
.map-container {
  border-radius: var(--radius-2xl);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  height: 400px;
  background: var(--slate-100);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--slate-500);
}

/* 工具提示 */
.tooltip {
  position: relative;
}

.tooltip::after {
  content: attr(data-tooltip);
  position: absolute;
  bottom: 100%;
  left: 50%;
  transform: translateX(-50%) translateY(-8px);
  padding: 0.5rem 0.75rem;
  background: var(--slate-900);
  color: white;
  font-size: 0.75rem;
  border-radius: var(--radius-md);
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  transition: all var(--transition-fast);
}

.tooltip:hover::after {
  opacity: 1;
  transform: translateX(-50%) translateY(-4px);
}

/* 响应式设计 */
@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
  .hero-content { grid-template-columns: 1fr; text-align: center; }
  .hero-text { margin: 0 auto; }
  .hero-buttons { justify-content: center; }
  .case-study { grid-template-columns: 1fr; gap: 2rem; }
  .case-study.reverse { direction: ltr; }
  .stats { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  .navbar-menu {
    position: fixed;
    top: 72px;
    left: 0;
    right: 0;
    background: white;
    flex-direction: column;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--slate-200);
    box-shadow: var(--shadow-lg);
    transform: translateY(-100%);
    opacity: 0;
    pointer-events: none;
    transition: all var(--transition-base);
  }

  .navbar-menu.active {
    transform: translateY(0);
    opacity: 1;
    pointer-events: all;
  }

  .navbar-toggle {
    display: flex;
  }

  .navbar-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(6px, 6px);
  }

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

  .navbar-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(6px, -6px);
  }

  .grid-2,
  .grid-3,
  .grid-4 { grid-template-columns: 1fr; }

  .footer-grid { grid-template-columns: 1fr; }

  .section { padding: 4rem 0; }
  .section-lg { padding: 6rem 0; }

  .stats { grid-template-columns: 1fr; padding: 2rem; }

  .timeline::before { left: 20px; }
  .timeline-item,
  .timeline-item:nth-child(even) { justify-content: flex-start; }
  .timeline-content { width: calc(100% - 60px); margin-left: 60px !important; }
  .timeline-dot { left: 20px; }

  .footer-bottom { flex-direction: column; gap: 1rem; text-align: center; }
}

/* 工具类 */
.text-center { text-align: center; }
.text-gradient {
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }
.hidden { display: none; }

/* 可访问性 */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* 打印样式 */
@media print {
  .navbar,
  .footer,
  .btn { display: none; }

  body { font-size: 12pt; }

  .section { padding: 2rem 0; }
}