/* roulang page: index */
:root {
      --primary: #1A56DB;
      --primary-hover: #153EB0;
      --accent: #0CAF6B;
      --accent-glow: rgba(12, 175, 107, 0.3);
      --bg-white: #FFFFFF;
      --bg-light: #F4F7FC;
      --bg-dark: #1E293B;
      --text-heading: #0F172A;
      --text-body: #334155;
      --text-muted: #64748B;
      --text-light: #F1F5F9;
      --nav-text: #CBD5E1;
      --border-light: #E2E8F0;
      --border-input: #CBD5E1;
      --radius-card: 12px;
      --radius-btn: 8px;
      --shadow-card: 0 2px 8px rgba(0,0,0,0.04), 0 4px 16px rgba(0,0,0,0.04);
      --shadow-card-hover: 0 8px 24px rgba(0,0,0,0.08), 0 4px 12px rgba(0,0,0,0.04);
      --transition: 0.2s ease;
      --font-stack: 'Inter', 'SF Pro Text', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
    }
    * {
      box-sizing: border-box;
    }
    body {
      font-family: var(--font-stack);
      background-color: var(--bg-white);
      color: var(--text-body);
      margin: 0;
      line-height: 1.7;
      display: flex;
      flex-direction: row;
      min-height: 100vh;
    }
    h1, h2, h3 {
      color: var(--text-heading);
      font-weight: 600;
    }
    a {
      color: var(--primary);
      text-decoration: none;
      transition: var(--transition);
    }
    a:hover {
      color: var(--primary-hover);
    }
    img {
      max-width: 100%;
      height: auto;
    }
    /* 左侧竖向导航 */
    .sidebar-nav {
      width: 240px;
      height: 100vh;
      position: fixed;
      left: 0;
      top: 0;
      background-color: var(--bg-dark);
      display: flex;
      flex-direction: column;
      justify-content: space-between;
      padding: 32px 20px;
      z-index: 1030;
      box-shadow: 2px 0 12px rgba(0,0,0,0.06);
    }
    .nav-brand {
      text-align: center;
    }
    .nav-brand img {
      width: 140px;
      margin-bottom: 8px;
    }
    .nav-brand .tagline {
      font-size: 14px;
      color: #94A3B8;
      margin-top: 4px;
      letter-spacing: 0.3px;
    }
    .nav-links {
      display: flex;
      flex-direction: column;
      gap: 24px;
      margin-top: 48px;
      margin-bottom: auto;
    }
    .nav-links a {
      color: var(--nav-text);
      font-size: 16px;
      font-weight: 500;
      padding: 6px 12px;
      border-radius: 6px;
      transition: all 0.2s ease;
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .nav-links a i {
      font-size: 18px;
      opacity: 0.7;
    }
    .nav-links a:hover {
      color: white;
      background-color: rgba(255,255,255,0.08);
      transform: translateX(4px);
    }
    .nav-links a.active {
      color: white;
      border-left: 3px solid var(--accent);
      padding-left: 9px;
      background-color: rgba(255,255,255,0.05);
    }
    .sidebar-cta {
      margin-top: 32px;
      width: 100%;
    }
    .sidebar-cta .btn {
      width: 100%;
      background-color: white;
      color: var(--primary);
      font-weight: 600;
      border-radius: var(--radius-btn);
      padding: 12px 20px;
      border: none;
      transition: var(--transition);
    }
    .sidebar-cta .btn:hover {
      background-color: #e9ecef;
    }
    /* 右侧主内容 */
    .main-content {
      margin-left: 240px;
      width: calc(100% - 240px);
      background-color: var(--bg-white);
    }
    /* 移动端导航 */
    .mobile-nav {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 64px;
      background-color: var(--bg-dark);
      z-index: 1040;
      align-items: center;
      justify-content: space-between;
      padding: 0 20px;
    }
    .mobile-nav .nav-brand-mobile img {
      height: 36px;
    }
    .navbar-toggler {
      border: none;
      color: white;
      font-size: 28px;
      background: transparent;
    }
    .mobile-menu {
      position: fixed;
      top: 64px;
      left: 0;
      width: 100%;
      background-color: var(--bg-dark);
      padding: 24px 20px;
      display: none;
      flex-direction: column;
      gap: 20px;
      z-index: 1039;
      box-shadow: 0 8px 20px rgba(0,0,0,0.2);
    }
    .mobile-menu a {
      color: var(--nav-text);
      font-size: 18px;
      font-weight: 500;
    }
    .mobile-menu a:hover {
      color: white;
    }
    /* 板块通用 */
    .section {
      padding: 120px 0;
    }
    .section-bg {
      background-color: var(--bg-light);
    }
    .container-custom {
      max-width: 1120px;
      margin: 0 auto;
      padding: 0 40px;
    }
    .section-title {
      font-size: 32px;
      font-weight: 600;
      margin-bottom: 16px;
      color: var(--text-heading);
    }
    .section-sub {
      font-size: 16px;
      color: var(--text-muted);
      margin-bottom: 48px;
    }
    /* 卡片 */
    .card-custom {
      background: white;
      border-radius: var(--radius-card);
      padding: 32px;
      box-shadow: var(--shadow-card);
      transition: all 0.2s ease;
      border: none;
      height: 100%;
    }
    .card-custom:hover {
      box-shadow: var(--shadow-card-hover);
      transform: translateY(-4px);
    }
    /* 按钮 */
    .btn-primary-custom {
      background-color: var(--primary);
      color: white;
      font-weight: 600;
      border-radius: var(--radius-btn);
      padding: 14px 32px;
      border: none;
      transition: var(--transition);
    }
    .btn-primary-custom:hover {
      background-color: var(--primary-hover);
      box-shadow: 0 6px 18px rgba(26,86,219,0.25);
      color: white;
    }
    .btn-outline-link {
      color: var(--primary);
      font-weight: 600;
      background: transparent;
      border: none;
      padding: 0;
    }
    .btn-outline-link i {
      transition: transform 0.2s;
    }
    .btn-outline-link:hover i {
      transform: translateX(4px);
    }
    /* 表单 */
    .form-control-custom {
      height: 48px;
      border: 1px solid var(--border-input);
      border-radius: var(--radius-btn);
      padding: 0 16px;
      font-size: 16px;
      transition: 0.2s;
    }
    .form-control-custom:focus {
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgba(26,86,219,0.15);
      outline: none;
    }
    /* Hero */
    .hero-title {
      font-size: 48px;
      font-weight: 700;
      line-height: 1.2;
      letter-spacing: -0.5px;
      color: var(--text-heading);
    }
    .hero-metrics .metric-number {
      font-size: 40px;
      font-weight: 700;
      color: var(--accent);
      line-height: 1.1;
    }
    /* 对比区块 */
    .comparison-left {
      background-color: #F1F5F9;
      border-radius: var(--radius-card);
      padding: 32px;
    }
    .comparison-right {
      background-color: #EBF3FF;
      border-radius: var(--radius-card);
      padding: 32px;
    }
    .divider-dotted {
      border-left: 1px dashed var(--border-input);
      height: auto;
    }
    /* FAQ */
    .accordion-button-custom {
      background: white;
      border: none;
      border-bottom: 1px solid var(--border-light);
      font-weight: 600;
      padding: 20px 0;
      text-align: left;
      width: 100%;
      display: flex;
      justify-content: space-between;
      color: var(--text-heading);
    }
    .accordion-body-custom {
      padding: 0 0 20px 20px;
      color: #475569;
    }
    @media (max-width: 768px) {
      .sidebar-nav {
        display: none;
      }
      .mobile-nav {
        display: flex;
      }
      .main-content {
        margin-left: 0;
        width: 100%;
        padding-top: 64px;
      }
      .section {
        padding: 80px 0;
      }
      .container-custom {
        padding: 0 20px;
      }
      .hero-title {
        font-size: 36px;
      }
      .section-title {
        font-size: 26px;
      }
      .card-custom {
        padding: 24px;
      }
      .divider-dotted {
        display: none;
      }
    }