/* roulang page: index */
:root {
      --primary-deep: #0A2E4B;
      --accent-orange: #F97316;
      --bg-light: #F8FAFC;
      --card-white: #FFFFFF;
      --text-main: #334155;
      --text-muted: #64748B;
      --radius-card: 12px;
      --radius-btn: 8px;
      --shadow-card: 0 4px 12px rgba(0,0,0,0.04), 0 1px 2px rgba(0,0,0,0.06);
      --shadow-card-hover: 0 10px 25px rgba(0,0,0,0.08);
      --transition-smooth: 0.25s ease;
    }

    * {
      box-sizing: border-box;
    }

    body {
      margin: 0;
      font-family: 'PingFang SC', 'Microsoft YaHei', 'Segoe UI', 'Helvetica Neue', sans-serif;
      background-color: var(--bg-light);
      color: var(--text-main);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }

    img {
      max-width: 100%;
      height: auto;
      display: block;
    }

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

    /* 导航栏固定白底 */
    .main-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: var(--card-white);
      box-shadow: 0 1px 6px rgba(0,0,0,0.05);
      z-index: 50;
      transition: var(--transition-smooth);
    }

    .nav-link {
      color: var(--primary-deep);
      font-weight: 500;
      padding: 0.5rem 0.25rem;
      margin: 0 1rem;
      text-decoration: none;
      border-bottom: 2px solid transparent;
      transition: color 0.2s, border-color 0.2s;
    }

    .nav-link:hover {
      color: var(--accent-orange);
      border-bottom-color: var(--accent-orange);
    }

    .mobile-menu {
      display: none;
    }

    /* 汉堡菜单全屏覆盖 */
    .mobile-overlay {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: var(--primary-deep);
      flex-direction: column;
      justify-content: center;
      align-items: center;
      z-index: 60;
      display: none;
    }
    .mobile-overlay.active {
      display: flex;
    }
    .mobile-overlay a {
      color: white;
      font-size: 1.8rem;
      margin: 1.2rem 0;
      text-decoration: none;
      font-weight: 500;
      letter-spacing: 1px;
    }

    /* 按钮系统 */
    .btn-primary {
      background: var(--accent-orange);
      color: white;
      border-radius: var(--radius-btn);
      padding: 0.75rem 2rem;
      font-weight: 600;
      display: inline-block;
      text-decoration: none;
      border: none;
      cursor: pointer;
      transition: background 0.2s, box-shadow 0.2s;
      box-shadow: 0 2px 8px rgba(249,115,22,0.3);
    }
    .btn-primary:hover {
      background: #EA580C;
      box-shadow: 0 6px 14px rgba(249,115,22,0.4);
    }
    .btn-secondary {
      background: transparent;
      color: var(--primary-deep);
      border: 1.5px solid var(--primary-deep);
      border-radius: var(--radius-btn);
      padding: 0.75rem 2rem;
      font-weight: 600;
      display: inline-block;
      text-decoration: none;
      cursor: pointer;
      transition: background 0.2s, color 0.2s;
    }
    .btn-secondary:hover {
      background: #E0F2FE;
      color: #0A2E4B;
    }

    /* 卡片通用 */
    .card {
      background: var(--card-white);
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      padding: 1.5rem;
      transition: transform var(--transition-smooth), box-shadow var(--transition-smooth);
    }
    .card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-card-hover);
    }

    /* 手风琴样式 */
    .faq-item {
      border-bottom: 1px solid #E2E8F0;
      padding: 1.2rem 0;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      font-weight: 600;
      color: var(--primary-deep);
      font-size: 1.2rem;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      color: var(--text-main);
      padding-right: 2rem;
    }
    .faq-answer.open {
      max-height: 200px;
      padding-top: 0.8rem;
    }

    /* 英雄区域图片微倾斜 */
    .hero-image-wrapper {
      border-radius: 16px;
      overflow: hidden;
      box-shadow: 0 20px 35px rgba(0,0,0,0.1);
      transform: rotate(-0.8deg);
      transition: transform 0.3s;
    }
    .hero-image-wrapper:hover {
      transform: rotate(0deg);
    }

    /* 案例卡片覆盖层 */
    .case-card {
      border-radius: var(--radius-card);
      overflow: hidden;
      position: relative;
      break-inside: avoid;
      margin-bottom: 1.5rem;
    }
    .case-overlay {
      position: absolute;
      bottom: 0;
      left: 0;
      right: 0;
      background: linear-gradient(to top, rgba(0,0,0,0.7), transparent);
      color: white;
      padding: 1.5rem;
      transition: background 0.3s;
    }
    .case-card:hover .case-overlay {
      background: linear-gradient(to top, rgba(0,0,0,0.85), rgba(0,0,0,0.2));
    }

    /* 对比组件 */
    .compare-col {
      border-radius: var(--radius-card);
      padding: 2rem;
    }