/* ============================================
   字体引入
   ============================================ */
@import url('https://fonts.googleapis.com/css2?family=Inter:opsz,wght@14..32,300;14..32,400;14..32,500;14..32,600;14..32,700;14..32,800&display=swap');

/* ============================================
   设计令牌 (Design Tokens)
   ============================================ */
:root {
  --primary: #3B82F6;
  --primary-dark: #2563EB;
  --primary-darker: #1D4ED8;
  --primary-light: #EFF6FF;
  --primary-lighter: #F5F9FF;
  --primary-soft: rgba(59, 130, 246, 0.1);
  --primary-medium: rgba(59, 130, 246, 0.2);
  --secondary: #6366F1;
  --secondary-dark: #4F46E5;
  --secondary-light: #EEF2FF;
  --accent: #06B6D4;
  --accent-dark: #0891B2;
  --success: #10B981;
  --warning: #F59E0B;
  --error: #EF4444;
  --info: #3B82F6;
  --text-primary: #0F172A;
  --text-secondary: #334155;
  --text-tertiary: #64748B;
  --text-quaternary: #94A3B8;
  --text-light: #CBD5E1;
  --text-on-primary: #FFFFFF;
  --text-on-primary-secondary: #E2E8F0;
  --text-on-dark: #FFFFFF;
  --text-on-dark-secondary: #E2E8F0;
  --bg-body: #F9FAFB;
  --bg-primary: #FFFFFF;
  --bg-secondary: #F3F4F6;
  --bg-tertiary: #F1F5F9;
  --bg-card: #FFFFFF;
  --bg-card-hover: #FFFFFF;
  --bg-inset: #F8FAFC;
  --bg-footer: #1E293B;
  --border: #E2E8F0;
  --border-light: #F1F5F9;
  --border-medium: #CBD5E1;
  --border-primary-soft: rgba(59, 130, 246, 0.2);
  --border-focus: #3B82F6;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.03), 0 1px 1px rgba(0, 0, 0, 0.02);
  --shadow: 0 4px 6px -2px rgba(0, 0, 0, 0.03), 0 2px 4px -1px rgba(0, 0, 0, 0.02);
  --shadow-md: 0 10px 15px -6px rgba(0, 0, 0, 0.05), 0 4px 6px -2px rgba(0, 0, 0, 0.02);
  --shadow-lg: 0 20px 25px -12px rgba(0, 0, 0, 0.08), 0 8px 10px -6px rgba(0, 0, 0, 0.02);
  --shadow-xl: 0 25px 50px -12px rgba(0, 0, 0, 0.12);
  --shadow-hover: 0 30px 40px -20px rgba(0, 0, 0, 0.1), 0 10px 15px -8px rgba(0, 0, 0, 0.05);
  --shadow-primary: 0 8px 20px -6px rgba(59, 130, 246, 0.2);
  --shadow-primary-lg: 0 12px 28px -8px rgba(59, 130, 246, 0.25);
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-2xl: 32px;
  --radius-full: 9999px;
  --container: 1280px;
  --transition-default: all 0.25s cubic-bezier(0.2, 0.9, 0.4, 1.1);
  --transition-slow: all 0.35s cubic-bezier(0.2, 0.9, 0.4, 1.1);
}

/* ============================================
   基础重置
   ============================================ */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  background: var(--bg-body);
  font-family: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, 'Noto Sans', sans-serif;
  color: var(--text-secondary);
  line-height: 1.55;
  font-size: 16px;
}

a {
  text-decoration: none;
  transition: var(--transition-default);
}

a:not(.btn):not(.social-link):not(.footer-links-group a) {
  color: var(--text-secondary);
}

a:not(.btn):not(.social-link):not(.footer-links-group a):hover {
  color: var(--primary);
}

h1,
h2,
h3,
h4,
h5,
h6 {
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

h1 {
  font-size: 3rem;
}

h2 {
  font-size: 2.25rem;
  margin-bottom: 1rem;
}

h3 {
  font-size: 1.5rem;
}

h4 {
  font-size: 1.25rem;
}

h5 {
  font-size: 1.125rem;
}

h6 {
  font-size: 1rem;
}

.section-description,
.item-label,
.footer-brand p,
.service-features li,
.product-tags .tag {
  color: var(--text-tertiary);
}

/* ============================================
   布局工具
   ============================================ */
.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 32px;
}

section {
  padding: 80px 0;
  position: relative;
}

.services,
.about {
  background: var(--bg-secondary);
  border-top: 1px solid #E5E7EB;
  border-bottom: 1px solid #E5E7EB;
}


/* ============================================
   按钮组件
   ============================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.95rem;
  transition: var(--transition-default);
  cursor: pointer;
  border: none;
  line-height: 1;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: var(--text-on-primary);
  box-shadow: var(--shadow-primary);
}

.btn-primary:hover {
  transform: translateY(-2px);
  background: linear-gradient(135deg, var(--primary-dark), var(--primary-darker));
  box-shadow: var(--shadow-primary-lg);
}

.btn-secondary {
  background: var(--bg-primary);
  color: var(--primary);
  border: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
  border-color: var(--primary);
  background: var(--primary-lighter);
  transform: translateY(-2px);
}

.btn-outline {
  background: transparent;
  color: var(--primary);
  border: 1px solid var(--border-medium);
}

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

.btn-dark {
  background: rgba(255, 255, 255, 0.1);
  color: var(--text-on-dark);
  backdrop-filter: blur(8px);
  border: 1px solid rgba(255, 255, 255, 0.2);
}

.btn-dark:hover {
  background: rgba(255, 255, 255, 0.2);
  transform: translateY(-2px);
  border-color: rgba(255, 255, 255, 0.3);
}

.btn-sm {
  padding: 8px 20px;
  font-size: 0.85rem;
}

.btn-lg {
  padding: 16px 36px;
  font-size: 1.05rem;
}

.btn:disabled,
.btn.disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

/* ============================================
   头部导航
   ============================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-light);
  transition: all 0.3s;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 80px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.brand-logo {
  width: auto;
  height: 32px;
  display: flex;
  align-items: center;
}

.site-nav {
  display: flex;
  gap: 40px;
}

.site-nav a {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-secondary);
  padding: 4px 0;
  position: relative;
}

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

.site-nav a::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 50%;
  transform: translateX(-50%) scaleX(0);
  width: 100%;
  height: 2.5px;
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  border-radius: 2px;
  transition: transform 0.25s ease;
  transform-origin: center;
}

.site-nav a:hover::after,
.site-nav a.active::after {
  transform: translateX(-50%) scaleX(1);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 6px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  z-index: 101;
}

.nav-toggle span {
  width: 26px;
  height: 2px;
  background: var(--text-primary);
  transition: all 0.3s;
  border-radius: 2px;
}

/* ============================================
   区块头部
   ============================================ */
.section-header {
  text-align: center;
  max-width: 780px;
  margin: 0 auto 64px;
}

.section-badge {
  display: inline-block;
  padding: 6px 18px;
  background: var(--primary-light);
  color: var(--primary);
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 20px;
  box-shadow: var(--shadow-sm);
}

.section-header h2 {
  font-size: 2.8rem;
  font-weight: 800;
  margin-bottom: 20px;
  color: var(--text-primary);
}

.section-description {
  font-size: 1.2rem;
  line-height: 1.6;
  color: var(--text-secondary);
}

/* ============================================
   Hero 区域 - 带网格背景
   ============================================ */
.hero {
  position: relative;
  overflow: hidden;
  background: linear-gradient(135deg, #3B82F6 0%, #4F46E5 100%);
}

.hero-bg {
  position: absolute;
  inset: 0;
  overflow: hidden;
}

.hero-gradient {
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 20% 30%, rgba(59, 130, 246, 0.3) 0%, rgba(79, 70, 229, 0.3) 100%);
}

.hero-grid-pattern {
  position: absolute;
  inset: 0;
  background-image: linear-gradient(rgba(255, 255, 255, 0.08) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.08) 1px, transparent 1px);
  background-size: 70px 70px;
}

.hero-glow {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  opacity: 0.25;
  animation: glow 10s ease-in-out infinite;
}

.hero-glow-1 {
  width: 400px;
  height: 400px;
  background: #FFFFFF;
  top: -200px;
  right: -150px;
}

.hero-glow-2 {
  width: 350px;
  height: 350px;
  background: #C7D2FE;
  bottom: -150px;
  left: -100px;
  animation-delay: 5s;
}

@keyframes glow {

  0%,
  100% {
    transform: scale(1);
    opacity: 0.2;
  }

  50% {
    transform: scale(1.3);
    opacity: 0.4;
  }
}

.hero-container {
  position: relative;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
}

.hero-content {
  color: var(--text-on-dark);
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 20px;
  background: rgba(255, 255, 255, 0.15);
  border-radius: var(--radius-full);
  font-size: 0.9rem;
  font-weight: 500;
  margin-bottom: 28px;
  backdrop-filter: blur(8px);
}

.badge-dot {
  width: 8px;
  height: 8px;
  background: var(--success);
  border-radius: 50%;
  animation: pulse 2s infinite;
}

@keyframes pulse {

  0%,
  100% {
    opacity: 1;
    transform: scale(1);
  }

  50% {
    opacity: 0.6;
    transform: scale(1.2);
  }
}

.hero h1 {
  font-size: clamp(2.4rem, 8vw, 3.2rem);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 20px;
  letter-spacing: -0.03em;
  color: var(--text-on-dark);
  text-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
}

.hero-description {
  font-size: 1.2rem;
  line-height: 1.6;
  opacity: 0.95;
  margin-bottom: 30px;
  max-width: 540px;
  color: var(--text-on-dark-secondary);
  font-weight: 500;
}

.hero-buttons {
  display: flex;
  gap: 20px;
  margin-bottom: 40px;
  flex-wrap: wrap;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 20px;
  max-width: 480px;
}

.stat-item {
  text-align: left;
  padding: 16px 20px;
  background: rgba(255, 255, 255, 0.12);
  border-radius: var(--radius-xl);
  backdrop-filter: blur(4px);
  transition: transform 0.2s;
}

.stat-item:hover {
  transform: translateY(-4px);
  background: rgba(255, 255, 255, 0.18);
}

.stat-number {
  font-size: 1.8rem;
  font-weight: 800;
  margin-bottom: 6px;
  color: var(--text-on-dark);
}

.stat-label {
  font-size: 0.85rem;
  opacity: 0.9;
  color: var(--text-on-dark-secondary);
}

.hero-visual {
  position: relative;
}

.glass-card {
  position: relative;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(8px);
  border: 1px solid rgba(255, 255, 255, 0.6);
  border-radius: var(--radius-xl);
  padding: 16px 40px;
  box-shadow: 0 20px 35px -12px rgba(0, 0, 0, 0.2);
  overflow: hidden;
}

.float-card {
  position: absolute;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  border-radius: var(--radius-md);
  padding: 6px 12px;
  box-shadow: var(--shadow-lg);
  animation: floatCard 4s ease-in-out infinite;
}

.float-card-1 {
  top: -20px;
  right: -30px;
}

.float-card-2 {
  bottom: 60px;
  left: -40px;
  animation-delay: 2s;
}

.float-card svg,
.float-card img {
  width: 160px;
  height: auto;
  display: block;
}

@keyframes floatCard {

  0%,
  100% {
    transform: translateY(0);
  }

  50% {
    transform: translateY(-12px);
  }
}

/* ============================================
   产品卡片 (图片区域背景加深)
   ============================================ */
.products-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 36px;
}

.product-card {
  background: var(--bg-card);
  border-radius: var(--radius-xl);
  overflow: hidden;
  border: 1px solid var(--border);
  transition: var(--transition-slow);
  box-shadow: 0 8px 20px -6px rgba(0, 0, 0, 0.08);
}

.product-card:hover {
  transform: translateY(-10px);
  box-shadow: 0 20px 30px -12px rgba(0, 0, 0, 0.15);
  border-color: var(--border-medium);
}

.product-image {
  padding: 32px 24px;
  background: #E9EEF5;
  /* 加深背景，与白色卡片形成对比 */
  display: flex;
  align-items: center;
  justify-content: center;
}

.product-placeholder {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 10px 20px;
  background: var(--bg-footer);
  border-radius: var(--radius-md);
  font-weight: 500;
  color: var(--text-quaternary);
  border: 1px solid var(--border-light);
}

.product-info {
  padding: 28px;
}

.product-info h3 {
  font-size: 1.35rem;
  margin-bottom: 12px;
  color: var(--text-primary);
}

.big-teach {
  font-size: 2rem;
  font-weight: 700;
  display: inline-block;
  background: rgba(59, 130, 246, 0.12);
  padding: 2px 12px;
  border-radius: 48px;
  color: var(--primary);
  margin-right: 8px;
  backdrop-filter: blur(4px);
  letter-spacing: -0.02em;
  transform: translateY(-2px);
}

.product-info p {
  color: var(--text-secondary);
  line-height: 1.65;
  margin-bottom: 20px;
  font-size: 0.95rem;
}

.product-tags {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.tag {
  padding: 6px 14px;
  background: var(--bg-tertiary);
  color: var(--text-tertiary);
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  font-weight: 500;
}

/* ============================================
   学术团队卡片
   ============================================ */
.services-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 32px;
}

.service-card {
  background: var(--bg-card);
  border-radius: var(--radius-xl);
  padding: 32px 24px 40px;
  transition: all 0.35s cubic-bezier(0.2, 0.9, 0.4, 1.1);
  border: 1px solid var(--border);
  position: relative;
  box-shadow: 0 8px 20px -6px rgba(0, 0, 0, 0.08);
  text-align: center;
}

.service-card:hover {
  transform: translateY(-8px);
  box-shadow: 0 20px 30px -12px rgba(0, 0, 0, 0.15);
  border-color: var(--border-medium);
}

.service-icon {
  width: 128px;
  height: 128px;
  margin: 0 auto 24px;
  position: relative;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary-light), #fff);
  padding: 4px;
  box-shadow: 0 12px 24px -8px rgba(59, 130, 246, 0.2);
  transition: all 0.3s ease;
}

.service-icon::after {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  opacity: 0;
  transition: opacity 0.3s ease;
  z-index: 0;
}

.service-card:hover .service-icon::after {
  opacity: 1;
}

.service-icon img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 50%;
  position: relative;
  z-index: 1;
  transition: transform 0.3s ease;
}

.service-card:hover .service-icon img {
  transform: scale(1.02);
}

.service-card h3 {
  font-size: 1.6rem;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.service-title {
  display: inline-block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--primary);
  background: var(--primary-light);
  padding: 6px 18px;
  border-radius: 40px;
  margin-bottom: 20px;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.5), 0 1px 2px rgba(0, 0, 0, 0.02);
}

.service-card>p {
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 24px;
  font-size: 0.9rem;
  text-align: center;
  padding: 0 8px;
}

.service-features {
  list-style: none;
  margin-top: 8px;
  padding-top: 20px;
  border-top: 1px solid var(--border-light);
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
}

.service-features li {
  background: var(--bg-tertiary);
  color: var(--text-tertiary);
  font-size: 0.75rem;
  font-weight: 500;
  padding: 6px 14px;
  border-radius: 40px;
  transition: all 0.2s;
}

.service-card:hover .service-features li {
  background: var(--primary-light);
  color: var(--primary);
}

/* ============================================
   关于区域
   ============================================ */
.about-content h2 {
  font-size: 2.6rem;
  font-weight: 800;
  margin-bottom: 24px;
  color: var(--text-primary);
}

.about-description {
  font-size: 1.15rem;
  line-height: 1.7;
  margin-bottom: 40px;
  color: var(--text-secondary);
}

.about-features {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 28px;
  margin-top: 40px;
  padding-bottom: 20px;
}

.feature-item {
  display: flex;
  gap: 24px;
  align-items: flex-start;
  background: var(--bg-card);
  border-radius: var(--radius-xl);
  padding: 28px 24px;
  border: 1px solid #EDF2F7;
  box-shadow: 0 4px 12px -4px rgba(0, 0, 0, 0.05);
  transition: all 0.3s ease;
}

.feature-item:hover {
  box-shadow: 0 12px 24px -8px rgba(0, 0, 0, 0.1);
  transform: translateY(-2px);
  border-color: var(--border);
}

.feature-icon {
  width: 56px;
  height: 56px;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--primary-light);
  border-radius: var(--radius-lg);
  color: var(--primary);
  box-shadow: var(--shadow-sm);
}

.feature-item h4 {
  font-size: 1.25rem;
  margin-bottom: 8px;
  color: var(--text-primary);
}

.feature-item p {
  color: var(--text-tertiary);
  line-height: 1.5;
  font-size: 0.9rem;
  margin: 0;
}

/* ============================================
   下载模块
   ============================================ */

.app-download_cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
  margin-top: 32px;
}

.app-download_card {
  background: var(--bg-card);
  border-radius: var(--radius-xl);
  padding: 32px 24px;
  text-align: center;
  border: 1px solid var(--border);
  transition: var(--transition-default);
  box-shadow: 0 8px 20px -6px rgba(0, 0, 0, 0.08);
  position: relative;
}

.app-download_card:hover {
  box-shadow: 0 20px 30px -12px rgba(0, 0, 0, 0.15);
  border-color: var(--border-medium);
}

.app-download_icon {
  width: 72px;
  height: 72px;
  margin: 0 auto 20px;
  background: #EFF6FF;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary);
  transition: var(--transition-default);
}

.app-download_card:hover .app-download_icon {
  background: var(--primary);
  color: white;
}

.app-download_card h3 {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 12px;
  color: var(--text-primary);
}

.app-download_card p {
  color: var(--text-tertiary);
  font-size: 0.9rem;
  line-height: 1.5;
  margin-bottom: 16px;
}

.app-download_link {
  display: inline-block;
  font-size: 0.75rem;
  color: var(--primary);
  word-break: break-all;
  background: var(--primary-light);
  padding: 6px 12px;
  border-radius: var(--radius-full);
  text-decoration: none;
  transition: var(--transition-default);
}

.app-download_link:hover {
  background: var(--primary);
  color: white !important;
}

.app-download_badge {
  position: absolute;
  top: -12px;
  right: 20px;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: white;
  font-size: 0.7rem;
  font-weight: 600;
  padding: 4px 12px;
  border-radius: var(--radius-full);
  box-shadow: var(--shadow-sm);
}

.app-download_showcase {
  background: var(--bg-card);
  border-radius: var(--radius-xl);
  border: 1px solid var(--border);
  transition: var(--transition-default);
  box-shadow: 0 8px 20px -6px rgba(0, 0, 0, 0.08);
}

.app-download_showcase:hover {
  box-shadow: 0 20px 30px -12px rgba(0, 0, 0, 0.15);
  border-color: var(--border-medium);
}

.app-download_showcase img {
  display: block;
  width: 100%;
  border-radius: var(--radius-xl);
}

/* ============================================
   页脚 (含清晰备案链接)
   ============================================ */
.site-footer {
  background: var(--bg-footer);
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  padding: 60px 0 24px;
}

.footer-main {
  display: grid;
  grid-template-columns: 3fr 2fr 1fr;
  gap: 60px;
  padding-bottom: 48px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  margin-bottom: 32px;
}

.footer-brand-section {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.footer-description {
  color: #CBD5E1;
  font-size: 0.9rem;
  line-height: 1.7;
}

.footer-social {
  display: flex;
  gap: 16px;
}

.social-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  background: rgba(255, 255, 255, 0.08);
  border-radius: var(--radius-full);
  color: #E2E8F0;
  font-size: 0.85rem;
  font-weight: 500;
  transition: var(--transition-default);
  border: 1px solid rgba(255, 255, 255, 0.1);
}

.social-link:hover {
  background: var(--primary);
  color: var(--text-on-primary);
  border-color: var(--primary);
}

.social-link svg {
  flex-shrink: 0;
}

.footer-links-section {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 32px;
}

.footer-links-group h4 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 20px;
  color: #F1F5F9;
  position: relative;
  display: inline-block;
}

.footer-links-group h4::after {
  content: '';
  position: absolute;
  bottom: -8px;
  left: 0;
  width: 30px;
  height: 2px;
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  border-radius: 2px;
}

.footer-links-group ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.footer-links-group a {
  color: #CBD5E1;
  font-size: 0.85rem;
  transition: var(--transition-default);
}

.footer-links-group a:hover {
  color: var(--primary);
  display: inline-block;
}

.footer-qrcode {
  display: flex;
  justify-content: flex-end;
}

.qrcode-card {
  background: rgba(255, 255, 255, 0.05);
  border-radius: var(--radius-lg);
  padding: 20px;
  text-align: center;
  border: 1px solid rgba(255, 255, 255, 0.1);
  transition: var(--transition-default);
}

.qrcode-card:hover {
  background: rgba(255, 255, 255, 0.1);
}

.qrcode-card img {
  width: 120px;
  height: 120px;
  border-radius: var(--radius-md);
  margin-bottom: 12px;
}

.qrcode-card p {
  font-size: 0.85rem;
  font-weight: 600;
  color: #F1F5F9;
}

.footer-copyright {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-copyright p {
  color: #94A3B8;
  font-size: 0.8rem;
}

.footer-legal-links {
  display: flex;
  align-items: center;
  gap: 32px;
  flex-wrap: wrap;
}

.footer-legal-links a,
.footer-legal-links a:link,
.footer-legal-links a:visited {
  color: #94A3B8 !important;
  font-size: 0.75rem;
  font-weight: 500;
  text-decoration: none;
  transition: color 0.2s;
}

.footer-legal-links a:hover {
  color: var(--primary) !important;
}

.footer-legal-links .separator {
  color: var(--bg-footer);
  font-weight: 400;
}

/* ============================================
   返回顶部按钮
   ============================================ */
.back-to-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  width: 52px;
  height: 52px;
  border: none;
  border-radius: var(--radius-full);
  background: var(--primary);
  color: var(--text-on-primary);
  font-size: 1.4rem;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: var(--transition-default);
  z-index: 1000;
  box-shadow: var(--shadow-lg);
  display: flex;
  align-items: center;
  justify-content: center;
}

.back-to-top.is-visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  transform: translateY(-6px);
  background: var(--primary-dark);
  box-shadow: var(--shadow-xl);
}

/* ============================================
   动画与交互相应
   ============================================ */
[data-reveal] {
  opacity: 0;
  transform: translateY(40px);
  transition: all 0.7s cubic-bezier(0.2, 0.9, 0.4, 1.1);
}

[data-reveal].revealed {
  opacity: 1;
  transform: translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  [data-reveal] {
    transition: none;
    transform: none;
    opacity: 1;
  }

  .float-card,
  .hero-glow {
    animation: none;
  }
}

/* ============================================
   响应式设计
   ============================================ */
@media (max-width: 1024px) {
  .container {
    padding: 0 24px;
  }

  .hero-container {
    grid-template-columns: 1fr;
    gap: 50px;
  }

  .hero-visual {
    order: -1;
  }

  .services-grid,
  .products-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 30px;
  }

  .footer-main {
    grid-template-columns: 1fr 1.5fr;
    gap: 40px;
  }

  .footer-qrcode {
    grid-column: span 2;
    justify-content: flex-start;
  }

  .service-icon {
    width: 100px;
    height: 100px;
  }

  .service-card h3 {
    font-size: 1.4rem;
  }

  body {
    font-size: 16px;
  }

  h2 {
    font-size: 2.2rem;
  }

  .section-header h2 {
    font-size: 2.5rem;
  }

  .hero h1 {
    font-size: 2.5rem;
  }

  .hero-description {
    font-size: 1.2rem;
  }

  .stat-number {
    font-size: 1.6rem;
  }

  .stat-label {
    font-size: 0.9rem;
  }

  .section-description {
    font-size: 1.15rem;
  }

  .app-download_cards {
    gap: 24px;
    margin: 24px 0;
  }

  .app-download_card {
    padding: 24px 20px;
  }
}

@media (max-width: 768px) {
  .container {
    padding: 0 20px;
  }

  section {
    padding: 60px 0;
  }

  .site-nav {
    position: fixed;
    top: 80px;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(20px);
    flex-direction: column;
    padding: 32px 24px;
    gap: 20px;
    box-shadow: var(--shadow-lg);
    transform: translateY(-120%);
    opacity: 0;
    visibility: hidden;
    transition: transform 0.3s ease, opacity 0.2s;
    border-top: 1px solid var(--border);
    border-bottom: 1px solid var(--border);
    z-index: 99;
  }

  .site-nav.active {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }

  body.menu-open {
    overflow: hidden;
  }

  .site-nav a {
    padding: 14px 20px;
    font-size: 1.2rem;
    font-weight: 500;
    border-left: 3px solid transparent;
  }

  .site-nav a.active {
    background: var(--primary-soft);
    border-left-color: var(--primary);
  }

  .nav-toggle {
    display: flex;
  }

  body {
    font-size: 16px;
  }

  h2 {
    font-size: 2rem;
  }

  .section-header h2,
  .about-content h2 {
    font-size: 2.2rem;
  }

  .section-description,
  .hero-description,
  .about-description {
    font-size: 1.1rem;
  }

  .hero {
    padding: 60px 0;
  }

  .hero h1 {
    font-size: 2.2rem;
  }

  .hero-badge {
    font-size: 1rem;
    padding: 6px 18px;
  }

  .hero-buttons {
    flex-direction: column;
    align-items: stretch;
  }

  .hero-stats {
    grid-template-columns: 1fr 1fr;
    gap: 12px;
  }

  .stat-item {
    padding: 14px 16px;
  }

  .stat-number {
    font-size: 1.4rem;
  }

  .stat-label {
    font-size: 0.85rem;
  }

  .section-header {
    margin-bottom: 40px;
  }

  .section-badge {
    font-size: 0.9rem;
    padding: 6px 18px;
  }

  .services-grid,
  .products-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .product-image {
    padding: 32px 24px;
  }

  .product-info {
    padding: 24px;
  }

  .product-info h3 {
    font-size: 1.3rem;
  }

  .product-info p {
    font-size: 1rem;
  }

  .tag {
    font-size: 0.8rem;
    padding: 6px 14px;
  }

  .big-teach {
    font-size: 1.8rem;
    padding: 2px 10px;
  }

  .service-card {
    padding: 24px 20px 32px;
  }

  .service-icon {
    width: 104px;
    height: 104px;
    margin-bottom: 20px;
  }

  .service-card h3 {
    font-size: 1.4rem;
  }

  .service-title {
    font-size: 0.8rem;
    padding: 4px 14px;
  }

  .service-card>p {
    font-size: 0.95rem;
  }

  .service-features li {
    font-size: 0.9rem;
  }

  .about-features {
    grid-template-columns: 1fr !important;
    gap: 20px;
  }

  .feature-item {
    padding: 20px;
    gap: 16px;
  }

  .feature-icon {
    width: 48px;
    height: 48px;
  }

  .feature-item h4 {
    font-size: 1.1rem;
  }

  .feature-item p {
    font-size: 0.95rem;
  }

  .app-download {
    padding: 60px 0;
  }

  .app-download_cards {
    grid-template-columns: 1fr;
    gap: 24px;
    margin: 24px 0;
  }

  .app-download_card {
    padding: 24px 20px;
  }

  .app-download_link {
    font-size: 0.7rem;
  }

  .footer-main {
    grid-template-columns: 1fr;
    gap: 36px;
  }

  .footer-links-section {
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
  }

  .footer-qrcode {
    grid-column: auto;
    justify-content: center;
  }

  .footer-copyright {
    flex-direction: column;
    text-align: center;
  }

  .footer-legal-links {
    justify-content: center;
  }

  .float-card-1 {
    top: -20px;
    right: -15px;
  }

  .float-card-2 {
    bottom: 40px;
    left: -25px;
  }

  .float-card svg,
  .float-card img {
    width: 160px;
  }

  .back-to-top {
    bottom: 20px;
    right: 20px;
    width: 48px;
    height: 48px;
    font-size: 1.4rem;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 16px;
  }

  section {
    padding: 50px 0;
  }

  body {
    font-size: 16px;
  }

  h2 {
    font-size: 1.8rem;
  }

  .section-header h2,
  .about-content h2 {
    font-size: 2rem;
  }

  .section-description {
    font-size: 1rem;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .hero-description {
    font-size: 1rem;
  }

  .btn {
    padding: 12px 24px;
    font-size: 1rem;
  }

  .stat-number {
    font-size: 1.2rem;
  }

  .stat-label {
    font-size: 0.8rem;
  }

  .product-info h3 {
    font-size: 1.2rem;
  }

  .product-info p {
    font-size: 0.95rem;
  }

  .tag {
    font-size: 0.75rem;
  }

  .service-icon {
    width: 90px;
    height: 90px;
  }

  .service-card h3 {
    font-size: 1.4rem;
  }

  .service-title {
    font-size: 0.8rem;
  }

  .service-card>p {
    font-size: 0.9rem;
  }

  .service-features li {
    font-size: 0.85rem;
  }

  .feature-icon {
    width: 46px;
    height: 46px;
  }

  .feature-item h4 {
    font-size: 1.1rem;
  }

  .feature-item p {
    font-size: 0.9rem;
  }

  .footer-links-section {
    grid-template-columns: 1fr;
    gap: 28px;
  }

  .footer-social {
    flex-direction: column;
    align-items: flex-start;
  }

  .social-link {
    width: 100%;
    justify-content: center;
  }

  .qrcode-card {
    padding: 16px;
  }

  .qrcode-card img {
    width: 100px;
    height: 100px;
  }

  .footer-legal-links {
    flex-direction: column;
    gap: 8px;
  }

  .float-card svg,
  .float-card img {
    width: 100px;
  }

  .glass-card {
    padding: 8px 16px;
    border-radius: var(--radius-lg);
  }
}