/* roulang page: index */
:root {
      --primary: #1A5FDC;
      --primary-hover: #1550B8;
      --accent: #F57C00;
      --bg: #FAFBFD;
      --card-bg: #FFFFFF;
      --light-blue: #F1F6FD;
      --text-heading: #0F172A;
      --text-body: #334155;
      --text-muted: #64748B;
      --border-light: #E2E8F0;
      --shadow-sm: 0 1px 3px rgba(0,0,0,0.06), 0 4px 12px rgba(0,0,0,0.04);
      --shadow-hover: 0 4px 16px rgba(26,95,220,0.12), 0 8px 24px rgba(0,0,0,0.06);
      --radius-card: 12px;
      --radius-btn: 8px;
      --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    }
    * {
      box-sizing: border-box;
    }
    body {
      font-family: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
      background-color: var(--bg);
      color: var(--text-body);
      line-height: 1.7;
      margin: 0;
      -webkit-font-smoothing: antialiased;
    }
    .container {
      max-width: 1200px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 20px;
      padding-right: 20px;
    }
    h1, h2, h3, h4 {
      color: var(--text-heading);
      font-weight: 700;
      line-height: 1.3;
    }
    h1 {
      font-size: clamp(2rem, 5vw, 3rem);
    }
    h2 {
      font-size: clamp(1.75rem, 4vw, 2.25rem);
      margin-bottom: 1rem;
    }
    h3 {
      font-size: 1.25rem;
    }
    .section-padding {
      padding: 5rem 0;
    }
    @media (max-width: 768px) {
      .section-padding {
        padding: 3.5rem 0;
      }
    }
    /* 导航 */
    .navbar {
      height: 64px;
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(8px);
      box-shadow: 0 1px 3px rgba(0,0,0,0.04);
      position: sticky;
      top: 0;
      z-index: 50;
    }
    .nav-link {
      font-size: 0.95rem;
      color: #475569;
      position: relative;
      transition: var(--transition);
      text-decoration: none;
    }
    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 50%;
      transform: translateX(-50%) scaleX(0);
      width: 100%;
      height: 2px;
      background: var(--primary);
      transition: transform 0.25s ease;
    }
    .nav-link:hover {
      color: var(--primary);
    }
    .nav-link:hover::after {
      transform: translateX(-50%) scaleX(1);
    }
    .active-nav {
      color: var(--primary);
      font-weight: 600;
    }
    .active-nav::after {
      transform: translateX(-50%) scaleX(1);
    }
    .btn-primary {
      background: var(--primary);
      color: white;
      border-radius: var(--radius-btn);
      padding: 0.7rem 1.8rem;
      font-weight: 600;
      transition: var(--transition);
      box-shadow: 0 2px 8px rgba(26,95,220,0.2);
      border: none;
      cursor: pointer;
      display: inline-block;
      text-decoration: none;
    }
    .btn-primary:hover {
      background: var(--primary-hover);
      transform: translateY(-2px);
      box-shadow: var(--shadow-hover);
    }
    .btn-outline {
      background: white;
      border: 2px solid var(--primary);
      color: var(--primary);
      border-radius: var(--radius-btn);
      padding: 0.7rem 1.8rem;
      font-weight: 600;
      transition: var(--transition);
      text-decoration: none;
      display: inline-block;
    }
    .btn-outline:hover {
      background: #F1F6FD;
      transform: translateY(-2px);
    }
    .card {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
      padding: 2rem;
      height: 100%;
    }
    .card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
    }
    .icon-circle {
      width: 48px;
      height: 48px;
      background: rgba(26,95,220,0.1);
      border-radius: 12px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--primary);
      font-size: 1.5rem;
      margin-bottom: 1.2rem;
    }
    .input-field {
      width: 100%;
      padding: 0.9rem 1rem;
      border: 1px solid #CBD5E1;
      border-radius: 6px;
      background: white;
      transition: 0.2s;
    }
    .input-field:focus {
      outline: none;
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgba(26,95,220,0.15);
    }
    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }
    .faq-question {
      padding: 1rem 1.2rem;
      background: white;
      cursor: pointer;
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      align-items: center;
      transition: background 0.2s;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease, padding 0.3s ease;
      background: var(--light-blue);
      padding: 0 1.2rem;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding: 1rem 1.2rem;
    }
    .faq-item.active .faq-question {
      background: var(--light-blue);
    }
    .footer-dark {
      background: #0F172A;
      color: #CBD5E1;
    }
    @media (max-width: 768px) {
      .navbar {
        height: 56px;
      }
      .mobile-menu {
        position: fixed;
        top: 0;
        right: -100%;
        width: 280px;
        height: 100vh;
        background: white;
        box-shadow: -4px 0 12px rgba(0,0,0,0.1);
        transition: right 0.3s ease;
        z-index: 100;
        padding: 1.5rem;
        display: flex;
        flex-direction: column;
      }
      .mobile-menu.open {
        right: 0;
      }
      .mobile-menu a {
        padding: 0.8rem 0;
        font-size: 1.1rem;
        border-bottom: 1px solid #f1f5f9;
      }
    }
    .hero-image {
      border-radius: 16px;
      box-shadow: var(--shadow-sm);
      object-fit: cover;
      width: 100%;
      height: auto;
    }