/* roulang page: index */
:root {
      --primary: #0A0E27;
      --accent-cyan: #00F0FF;
      --accent-red: #FF4655;
      --bg-light: #F5F7FA;
      --bg-dark: #0F1420;
      --card-white: #FFFFFF;
      --border-light: #EFF1F5;
      --text-body: #1E293B;
      --text-muted: #64748B;
      --shadow-sm: 0px 4px 20px rgba(0,0,0,0.04);
      --shadow-md: 0px 8px 30px rgba(0,240,255,0.08);
      --shadow-red: 0px 4px 14px rgba(255,70,85,0.4);
      --radius-card: 16px;
      --radius-btn: 8px;
      --font-heading: 'Inter', 'Noto Sans SC', system-ui, -apple-system, 'Segoe UI', sans-serif;
      --font-body: 'Noto Serif SC', 'Source Han Serif SC', Georgia, 'Times New Roman', serif;
    }

    * {
      box-sizing: border-box;
    }

    body {
      margin: 0;
      font-family: var(--font-body);
      background-color: var(--bg-light);
      color: var(--text-body);
      line-height: 1.75;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }

    h1, h2, h3, h4, .font-heading {
      font-family: var(--font-heading);
      letter-spacing: -0.02em;
    }

    .container-custom {
      max-width: 1280px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 1.5rem;
      padding-right: 1.5rem;
    }

    @media (max-width: 768px) {
      .container-custom {
        padding-left: 1rem;
        padding-right: 1rem;
      }
    }

    .card {
      background: var(--card-white);
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
      border: 1px solid var(--border-light);
      transition: all 0.25s ease;
    }

    .card:hover {
      box-shadow: var(--shadow-md);
      border-color: var(--accent-cyan);
      transform: translateY(-4px);
    }

    .btn-primary {
      background-color: var(--accent-red);
      color: white;
      border: none;
      border-radius: var(--radius-btn);
      padding: 12px 28px;
      font-weight: 600;
      font-family: var(--font-heading);
      font-size: 1rem;
      transition: all 0.2s ease;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 0.5rem;
      box-shadow: 0 4px 10px rgba(255,70,85,0.25);
      cursor: pointer;
      text-decoration: none;
      line-height: 1.2;
    }

    .btn-primary:hover {
      filter: brightness(1.1);
      box-shadow: 0 0 18px rgba(255,70,85,0.6);
      transform: scale(1.02);
    }

    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--primary);
      color: var(--primary);
      border-radius: var(--radius-btn);
      padding: 10px 26px;
      font-weight: 600;
      font-family: var(--font-heading);
      transition: all 0.25s;
      display: inline-flex;
      align-items: center;
      gap: 0.4rem;
      text-decoration: none;
    }

    .btn-outline:hover {
      background-color: rgba(10,14,39,0.08);
      border-color: var(--accent-cyan);
      color: #0A0E27;
    }

    .nav-link {
      color: var(--text-body);
      font-family: var(--font-heading);
      font-weight: 500;
      position: relative;
      transition: color 0.2s;
      text-decoration: none;
      font-size: 0.95rem;
    }

    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0%;
      height: 2px;
      background: var(--accent-cyan);
      transition: width 0.25s ease;
    }

    .nav-link:hover {
      color: var(--accent-cyan);
    }

    .nav-link:hover::after {
      width: 100%;
    }

    .faq-item {
      border-left: 4px solid var(--accent-cyan);
      background: #FFFFFF;
      border-radius: 12px;
      transition: all 0.3s;
      cursor: pointer;
      padding: 1.25rem 1.5rem;
      margin-bottom: 1rem;
      box-shadow: 0 2px 8px rgba(0,0,0,0.02);
    }

    .faq-item.active {
      border-left-color: var(--accent-red);
      background: #F8FAFC;
    }

    .faq-question {
      font-family: var(--font-heading);
      font-weight: 600;
      font-size: 1.1rem;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }

    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease, margin 0.2s;
      font-size: 0.95rem;
      color: #334155;
      margin-top: 0;
    }

    .faq-item.active .faq-answer {
      max-height: 200px;
      margin-top: 1rem;
    }

    /* 移动端底部导航 */
    .mobile-bottom-nav {
      display: none;
    }

    @media (max-width: 768px) {
      .desktop-nav {
        display: none;
      }
      .mobile-bottom-nav {
        display: flex;
        position: fixed;
        bottom: 0;
        left: 0;
        right: 0;
        background: rgba(255,255,255,0.96);
        backdrop-filter: blur(12px);
        border-top: 1px solid #E2E8F0;
        justify-content: space-around;
        padding: 0.5rem 0.25rem;
        z-index: 50;
        box-shadow: 0 -4px 15px rgba(0,0,0,0.05);
      }
      .mobile-nav-item {
        display: flex;
        flex-direction: column;
        align-items: center;
        font-size: 0.7rem;
        color: #475569;
        font-family: var(--font-heading);
        text-decoration: none;
        padding: 0.25rem;
      }
      .mobile-nav-item i {
        font-size: 1.2rem;
        margin-bottom: 2px;
      }
    }

    .hero-stat {
      border-left: 2px solid rgba(0,240,255,0.4);
      padding-left: 1.2rem;
    }