/* roulang page: index */
:root {
      --primary: #0A4DA4;
      --primary-dark: #083D82;
      --secondary: #00B4D8;
      --accent: #F59E0B;
      --bg: #F8FAFC;
      --card-bg: #FFFFFF;
      --text: #334155;
      --text-strong: #0F172A;
      --text-muted: #64748B;
      --border: #E2E8F0;
      --radius: 12px;
      --shadow-sm: 0 4px 6px -1px rgba(0,0,0,0.05), 0 2px 4px -2px rgba(0,0,0,0.05);
      --shadow-hover: 0 20px 25px -5px rgba(0,0,0,0.08), 0 8px 10px -6px rgba(0,0,0,0.04);
      --transition: 0.3s ease;
    }
    * {
      box-sizing: border-box;
    }
    body {
      margin: 0;
      font-family: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", sans-serif;
      background-color: var(--bg);
      color: var(--text);
      line-height: 1.7;
      -webkit-font-smoothing: antialiased;
      scroll-behavior: smooth;
    }
    .font-en {
      font-family: "Inter", "Segoe UI", sans-serif;
    }
    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 24px;
    }
    @media (max-width: 768px) {
      .container {
        padding: 0 16px;
      }
    }
    /* 导航栏 */
    .navbar {
      position: sticky;
      top: 0;
      z-index: 50;
      background: rgba(255,255,255,0.85);
      backdrop-filter: blur(8px);
      transition: background 0.3s;
    }
    .brand-row {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 64px;
    }
    .logo-text {
      font-size: 22px;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: -0.3px;
    }
    .channel-row {
      background: #F1F5F9;
      height: 48px;
      display: flex;
      align-items: center;
      overflow-x: auto;
      white-space: nowrap;
      scrollbar-width: none;
    }
    .channel-row::-webkit-scrollbar {
      display: none;
    }
    .channel-tab {
      padding: 12px 20px;
      font-size: 14px;
      font-weight: 500;
      color: var(--text-muted);
      text-decoration: none;
      transition: color 0.2s;
      border-bottom: 3px solid transparent;
    }
    .channel-tab:hover,
    .channel-tab.active {
      color: var(--primary);
      font-weight: 600;
      border-bottom-color: var(--primary);
    }
    .btn {
      display: inline-block;
      padding: 10px 24px;
      border-radius: 8px;
      font-weight: 600;
      font-size: 16px;
      letter-spacing: 0.5px;
      text-decoration: none;
      transition: background 0.2s, color 0.2s, border 0.2s;
      cursor: pointer;
    }
    .btn-primary {
      background: var(--primary);
      color: white;
      border: none;
    }
    .btn-primary:hover {
      background: var(--primary-dark);
    }
    .btn-outline {
      border: 2px solid var(--primary);
      color: var(--primary);
      background: transparent;
    }
    .btn-outline:hover {
      background: rgba(10,77,164,0.1);
    }
    .btn-white {
      border: 2px solid white;
      color: white;
      background: transparent;
    }
    .btn-white:hover {
      background: white;
      color: var(--primary);
    }
    /* 区块间距 */
    section {
      padding: 100px 0;
    }
    @media (max-width: 768px) {
      section {
        padding: 60px 0;
      }
    }
    .section-title {
      font-size: 38px;
      font-weight: 600;
      color: #1E293B;
      text-align: center;
      margin-bottom: 16px;
      position: relative;
    }
    .section-title::after {
      content: "";
      display: block;
      width: 40px;
      height: 2px;
      background: var(--primary);
      margin: 16px auto 0;
    }
    .hero {
      background: linear-gradient(135deg, #F8FAFC 0%, #E2E8F0 100%);
      min-height: 100vh;
      display: flex;
      align-items: center;
    }
    .card {
      background: var(--card-bg);
      border-radius: var(--radius);
      box-shadow: var(--shadow-sm);
      transition: transform var(--transition), box-shadow var(--transition);
    }
    .card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
    }
    .icon-circle {
      width: 48px;
      height: 48px;
      border-radius: 50%;
      background: rgba(0,180,216,0.1);
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--secondary);
      font-size: 24px;
    }
    /* 数字动画 */
    .count-up {
      font-size: 48px;
      font-weight: 700;
      color: var(--primary);
    }
    .accordion-header {
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 16px 0;
      font-weight: 600;
      color: #1E293B;
      border-bottom: 1px solid var(--border);
      transition: color 0.2s;
    }
    .accordion-header i {
      transition: transform 0.3s;
      color: var(--secondary);
    }
    .accordion-content {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
      color: #475569;
      padding: 0 16px;
    }
    .accordion-item.active .accordion-content {
      max-height: 200px;
      padding: 16px;
    }
    .accordion-item.active .accordion-header {
      color: var(--primary);
    }
    .accordion-item.active .accordion-header i {
      transform: rotate(180deg);
    }
    footer {
      background: #0F172A;
      color: #CBD5E1;
      padding: 60px 0 20px;
    }
    .footer-title {
      color: white;
      font-weight: 600;
      margin-bottom: 16px;
      position: relative;
    }
    .footer-title::after {
      content: "";
      display: block;
      width: 30px;
      height: 2px;
      background: var(--secondary);
      margin-top: 8px;
    }
    .social-icon {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      width: 36px;
      height: 36px;
      border-radius: 50%;
      border: 1px solid #64748B;
      color: #CBD5E1;
      margin-right: 8px;
      transition: 0.2s;
    }
    .social-icon:hover {
      border-color: var(--secondary);
      color: var(--secondary);
    }