/* roulang page: index */
:root {
      --primary: #E84A2D;
      --secondary: #1A1A2E;
      --accent: #F5A623;
      --bg: #F9F9FB;
      --text: #1E1E1E;
      --text-light: #5A5A5A;
      --card-bg: #FFFFFF;
      --border-light: #E5E5E5;
      --shadow-sm: 0 4px 20px rgba(0,0,0,0.04);
      --shadow-md: 0 8px 30px rgba(0,0,0,0.08);
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-input: 6px;
      --transition: 0.2s ease;
    }
    * {
      box-sizing: border-box;
    }
    body {
      margin: 0;
      font-family: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      background-color: var(--bg);
      color: var(--text);
      line-height: 1.7;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color var(--transition);
    }
    .container {
      max-width: 1200px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 20px;
      padding-right: 20px;
    }
    /* 导航栏 */
    .navbar {
      background-color: #fff;
      border-bottom: 1px solid var(--border-light);
      position: sticky;
      top: 0;
      z-index: 50;
      box-shadow: 0 2px 8px rgba(0,0,0,0.02);
    }
    .nav-brand {
      display: flex;
      align-items: center;
      gap: 8px;
      font-weight: 700;
      font-size: 1.5rem;
      color: var(--secondary);
    }
    .nav-brand i {
      color: var(--primary);
      font-size: 1.8rem;
    }
    .nav-channel a {
      font-weight: 500;
      font-size: 0.95rem;
      color: var(--text-light);
      padding: 8px 12px;
      border-bottom: 3px solid transparent;
      transition: all var(--transition);
      white-space: nowrap;
    }
    .nav-channel a:hover,
    .nav-channel a.active {
      color: var(--primary);
      border-bottom-color: var(--primary);
    }
    .hamburger-btn {
      display: none;
      background: none;
      border: none;
      font-size: 1.6rem;
      color: var(--secondary);
      cursor: pointer;
    }
    @media (max-width: 768px) {
      .nav-channel-desktop {
        display: none;
      }
      .hamburger-btn {
        display: block;
      }
      .mobile-menu {
        display: none;
        flex-direction: column;
        background: white;
        border-top: 1px solid var(--border-light);
      }
      .mobile-menu.open {
        display: flex;
      }
      .mobile-menu a {
        padding: 12px 20px;
        border-bottom: 1px solid #f0f0f0;
        font-weight: 500;
      }
    }
    /* 按钮 */
    .btn-primary {
      background-color: var(--primary);
      color: white;
      border: none;
      padding: 12px 28px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 1rem;
      cursor: pointer;
      transition: background-color var(--transition), transform var(--transition);
      display: inline-block;
      text-align: center;
    }
    .btn-primary:hover {
      background-color: #C53F26;
      transform: translateY(-1px);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--primary);
      color: var(--primary);
      padding: 10px 26px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      transition: all var(--transition);
    }
    .btn-outline:hover {
      background-color: rgba(232,74,45,0.08);
    }
    /* 卡片 */
    .card {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
      transition: all var(--transition);
    }
    .card:hover {
      box-shadow: var(--shadow-md);
      transform: translateY(-2px);
    }
    /* 手风琴 */
    .faq-item {
      border-bottom: 1px solid #eee;
    }
    .faq-question {
      font-weight: 600;
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 16px 0;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s ease;
      color: var(--text-light);
    }
    .faq-item.open .faq-answer {
      max-height: 200px;
      padding-bottom: 16px;
    }
    .faq-icon {
      color: var(--primary);
      font-weight: bold;
    }
    /* Hero数据卡片 */
    .metric-card {
      background: rgba(255,255,255,0.08);
      backdrop-filter: blur(6px);
      border-radius: 12px;
      padding: 16px;
      color: white;
    }
    .metric-number {
      font-size: 1.8rem;
      font-weight: 700;
      color: var(--accent);
    }
    /* 对比区块 */
    .compare-left {
      background: #F0F0F0;
      color: #6b6b6b;
    }
    .compare-right {
      background: white;
      border: 2px solid var(--primary);
    }
    /* 页脚 */
    .footer {
      background-color: var(--secondary);
      color: #ccc;
    }
    .footer a:hover {
      color: var(--primary);
    }