/* roulang page: index */
:root {
      --primary: #1A56DB;
      --primary-dark: #1E40AF;
      --primary-light: #3B82F6;
      --accent: #F97316;
      --accent-dark: #EA580C;
      --bg-light: #F8FAFC;
      --bg-white: #FFFFFF;
      --text-dark: #1E293B;
      --text-body: #475569;
      --text-muted: #94A3B8;
      --border-light: #E2E8F0;
      --shadow-sm: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
      --shadow-md: 0 10px 25px rgba(0,0,0,0.1);
      --radius-md: 12px;
      --radius-sm: 8px;
      --transition: 0.3s ease;
    }

    * {
      box-sizing: border-box;
    }

    body {
      font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif;
      margin: 0;
      background-color: var(--bg-white);
      color: var(--text-body);
      line-height: 1.7;
      -webkit-font-smoothing: antialiased;
    }

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

    /* 导航与顶部条 */
    .top-bar {
      background-color: #1E293B;
      color: #CBD5E1;
      font-size: 0.75rem;
      padding: 0.5rem 0;
    }
    .main-header {
      background: white;
      border-bottom: 1px solid var(--border-light);
      position: sticky;
      top: 0;
      z-index: 50;
    }
    .nav-link {
      color: var(--text-dark);
      font-weight: 500;
      padding: 0.5rem 1rem;
      transition: color 0.2s;
      position: relative;
      text-decoration: none;
    }
    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -2px;
      left: 1rem;
      right: 1rem;
      height: 2px;
      background: var(--primary);
      transform: scaleX(0);
      transition: transform 0.2s;
    }
    .nav-link:hover {
      color: var(--primary);
    }
    .nav-link:hover::after {
      transform: scaleX(1);
    }

    /* 按钮系统 */
    .btn-primary {
      background-color: var(--primary);
      color: white;
      border-radius: var(--radius-sm);
      padding: 0.75rem 2rem;
      font-weight: 600;
      display: inline-block;
      transition: background 0.2s, box-shadow 0.2s;
      text-decoration: none;
      border: none;
      cursor: pointer;
    }
    .btn-primary:hover {
      background-color: var(--primary-dark);
      box-shadow: 0 0 0 3px rgba(26,86,219,0.3);
    }
    .btn-accent {
      background-color: var(--accent);
      color: white;
      border-radius: var(--radius-sm);
      padding: 0.75rem 2.5rem;
      font-weight: 700;
      transition: background 0.2s, box-shadow 0.2s;
      text-decoration: none;
      display: inline-block;
      border: none;
      cursor: pointer;
    }
    .btn-accent:hover {
      background-color: var(--accent-dark);
      box-shadow: 0 0 0 4px rgba(249,115,22,0.3);
    }
    .btn-outline {
      background: transparent;
      border: 1px solid var(--primary);
      color: var(--primary);
      border-radius: var(--radius-sm);
      padding: 0.6rem 1.5rem;
      font-weight: 600;
      transition: all 0.2s;
      text-decoration: none;
      display: inline-block;
    }
    .btn-outline:hover {
      background: var(--primary);
      color: white;
    }

    /* 卡片系统 */
    .card {
      background: white;
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-sm);
      padding: 2rem;
      transition: transform 0.3s ease, box-shadow 0.3s ease;
      border-left: 4px solid var(--primary);
    }
    .card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-md);
    }

    /* FAQ 手风琴 */
    .faq-item {
      border: 1px solid var(--border-light);
      border-radius: var(--radius-sm);
      margin-bottom: 1rem;
      background: white;
      transition: border-color 0.2s;
    }
    .faq-item.active {
      border-color: var(--primary);
    }
    .faq-question {
      padding: 1.25rem 1.5rem;
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      color: var(--text-dark);
      font-size: 1.1rem;
    }
    .faq-answer {
      padding: 0 1.5rem 1.25rem;
      display: none;
      color: var(--text-body);
    }
    .faq-item.active .faq-answer {
      display: block;
    }
    .faq-arrow {
      transition: transform 0.3s;
      color: var(--primary);
    }
    .faq-item.active .faq-arrow {
      transform: rotate(180deg);
    }

    /* 装饰线条 */
    .decor-line {
      background: linear-gradient(90deg, var(--primary) 0%, transparent 100%);
      height: 4px;
      width: 60px;
      margin-top: 0.5rem;
      margin-bottom: 1.5rem;
    }

    /* 移动端菜单 */
    .mobile-menu {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100vh;
      background: rgba(255,255,255,0.98);
      z-index: 100;
      flex-direction: column;
      justify-content: center;
      align-items: center;
      gap: 2rem;
      font-size: 1.75rem;
    }
    .mobile-menu.open {
      display: flex;
    }
    @media (max-width: 768px) {
      .desktop-nav {
        display: none;
      }
      .hamburger {
        display: block;
      }
    }
    @media (min-width: 769px) {
      .hamburger {
        display: none;
      }
    }