/* roulang page: index */
:root {
      --primary: #0EA5E9;
      --primary-dark: #0284C7;
      --accent: #8B5CF6;
      --accent-dark: #7C3AED;
      --dark-bg: #1E293B;
      --darker-bg: #0F172A;
      --light-bg: #F8FAFC;
      --white: #FFFFFF;
      --gray-50: #F8FAFC;
      --gray-100: #F1F5F9;
      --gray-200: #E2E8F0;
      --gray-300: #CBD5E1;
      --gray-400: #94A3B8;
      --gray-500: #64748B;
      --gray-600: #475569;
      --gray-700: #334155;
      --gray-800: #1E293B;
      --gray-900: #0F172A;
      --shadow-card: 0 10px 25px -5px rgba(0,0,0,0.05), 0 8px 10px -6px rgba(0,0,0,0.02);
      --shadow-hover: 0 20px 30px -10px rgba(0,0,0,0.1), 0 10px 15px -6px rgba(0,0,0,0.05);
      --radius-lg: 16px;
      --radius-md: 12px;
      --radius-sm: 8px;
      --font-sans: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Noto Sans SC", system-ui, -apple-system, sans-serif;
    }

    * {
      box-sizing: border-box;
    }

    body {
      font-family: var(--font-sans);
      margin: 0;
      padding: 0;
      background-color: var(--white);
      color: var(--gray-700);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }

    .container {
      max-width: 1280px;
      margin: 0 auto;
      padding-left: 24px;
      padding-right: 24px;
    }

    @media (max-width: 640px) {
      .container {
        padding-left: 16px;
        padding-right: 16px;
      }
    }

    /* 导航栏 */
    .navbar {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(12px);
      border-bottom: 1px solid var(--gray-100);
      z-index: 50;
      transition: box-shadow 0.2s;
    }

    .navbar.scrolled {
      box-shadow: 0 4px 12px rgba(0,0,0,0.04);
    }

    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 68px;
    }

    .logo {
      display: flex;
      align-items: center;
      gap: 8px;
      font-weight: 700;
      font-size: 22px;
      color: var(--primary);
      text-decoration: none;
    }

    .logo-icon {
      font-size: 28px;
      color: var(--primary);
    }

    .nav-links {
      display: flex;
      align-items: center;
      gap: 24px;
    }

    .nav-link {
      color: var(--gray-600);
      font-weight: 500;
      text-decoration: none;
      transition: color 0.2s, border-bottom 0.2s;
      border-bottom: 2px solid transparent;
      padding-bottom: 4px;
      font-size: 15px;
    }

    .nav-link:hover {
      color: var(--primary);
      border-bottom-color: var(--primary);
    }

    .btn-primary-sm {
      background: var(--accent);
      color: white;
      padding: 10px 22px;
      border-radius: 30px;
      font-weight: 600;
      font-size: 15px;
      text-decoration: none;
      transition: background 0.2s, transform 0.1s;
      display: inline-block;
      box-shadow: 0 4px 10px rgba(139,92,246,0.25);
    }

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

    .hamburger {
      display: none;
      font-size: 24px;
      background: none;
      border: none;
      color: var(--gray-700);
      cursor: pointer;
    }

    .mobile-menu {
      display: none;
      flex-direction: column;
      background: white;
      padding: 20px 24px;
      gap: 16px;
      border-bottom: 1px solid var(--gray-100);
    }

    @media (max-width: 768px) {
      .nav-links {
        display: none;
      }
      .hamburger {
        display: block;
      }
      .mobile-menu.active {
        display: flex;
      }
    }

    /* 板块间距 */
    section {
      padding: 80px 0;
    }

    @media (max-width: 768px) {
      section {
        padding: 60px 0;
      }
    }

    .section-title {
      font-size: 32px;
      font-weight: 700;
      color: var(--gray-800);
      margin-bottom: 16px;
      position: relative;
      display: inline-block;
    }

    .section-title::after {
      content: '';
      position: absolute;
      left: 0;
      bottom: -8px;
      width: 48px;
      height: 4px;
      background: var(--primary);
      border-radius: 2px;
    }

    /* 卡片通用 */
    .card {
      background: white;
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-card);
      transition: all 0.3s ease;
      height: 100%;
    }

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

    /* 按钮系统 */
    .btn-solid {
      background: var(--primary);
      color: white;
      font-weight: 600;
      padding: 12px 28px;
      border-radius: 30px;
      text-decoration: none;
      display: inline-block;
      transition: background 0.2s, transform 0.1s;
      border: none;
      cursor: pointer;
      font-size: 16px;
    }

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

    .btn-outline {
      background: transparent;
      color: var(--primary);
      border: 2px solid var(--primary);
      font-weight: 600;
      padding: 12px 28px;
      border-radius: 30px;
      text-decoration: none;
      display: inline-block;
      transition: all 0.2s;
    }

    .btn-outline:hover {
      background: rgba(14,165,233,0.08);
    }

    .highlight-bar {
      width: 4px;
      background: var(--primary);
      border-radius: 2px;
      transition: width 0.2s;
    }

    .card:hover .highlight-bar {
      width: 6px;
      background: var(--accent);
    }