/* roulang page: index */
/* 自定义CSS变量与全局视觉系统 */
    :root {
      --color-primary-bg: #F0F2F5;
      --color-text-dark: #2C3E50;
      --color-accent: #00C9A7;
      --color-border: #E8ECF1;
      --color-card-bg: #FFFFFF;
      --font-sans: -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;
      --color-text-muted: #7F8C8D;
      --shadow-card: 0 2px 8px rgba(44, 62, 80, 0.04), 0 1px 2px rgba(44, 62, 80, 0.08);
      --shadow-hover: 0 8px 24px rgba(44, 62, 80, 0.08), 0 2px 4px rgba(44, 62, 80, 0.12);
      --border-radius-card: 8px;
      --border-radius-btn: 6px;
    }

    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: var(--font-sans);
      background-color: var(--color-primary-bg);
      color: var(--color-text-dark);
      line-height: 1.7;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
      padding-bottom: 80px; /* 为移动端底部导航留出空间 */
    }

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

    a {
      text-decoration: none;
      color: inherit;
      transition: color 0.2s;
    }

    button, input, textarea {
      font-family: inherit;
    }

    .container {
      max-width: 1280px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 24px;
      padding-right: 24px;
    }

    /* 自定义卡片样式 */
    .card {
      background-color: var(--color-card-bg);
      border: 1px solid var(--color-border);
      border-radius: var(--border-radius-card);
      box-shadow: var(--shadow-card);
      transition: all 0.25s ease;
    }

    .card:hover {
      border-color: var(--color-accent);
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
    }

    /* 按钮系统 */
    .btn-primary {
      background-color: var(--color-accent);
      color: white;
      border: none;
      border-radius: var(--border-radius-btn);
      padding: 12px 28px;
      font-weight: 600;
      font-size: 16px;
      cursor: pointer;
      transition: filter 0.2s, transform 0.1s;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
    }
    .btn-primary:hover {
      filter: brightness(0.9);
    }

    .btn-outline {
      background: transparent;
      color: var(--color-text-dark);
      border: 1px solid var(--color-text-dark);
      border-radius: var(--border-radius-btn);
      padding: 12px 28px;
      font-weight: 600;
      font-size: 16px;
      cursor: pointer;
      transition: all 0.25s;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
    }
    .btn-outline:hover {
      background-color: var(--color-text-dark);
      color: white;
      border-color: var(--color-text-dark);
    }

    /* 导航桌面端激活指示条 */
    .nav-link {
      position: relative;
      padding-bottom: 4px;
      font-weight: 500;
      color: var(--color-text-dark);
      transition: color 0.2s;
    }
    .nav-link::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 2px;
      background-color: var(--color-accent);
      transition: width 0.25s;
    }
    .nav-link:hover, .nav-link.active {
      color: var(--color-accent);
    }
    .nav-link:hover::after, .nav-link.active::after {
      width: 100%;
    }

    /* 移动端底部导航 (默认隐藏，小屏显示) */
    .mobile-bottom-nav {
      display: none;
      position: fixed;
      bottom: 0;
      left: 0;
      width: 100%;
      background: white;
      border-top: 1px solid var(--color-border);
      z-index: 1000;
      box-shadow: 0 -2px 8px rgba(0,0,0,0.02);
    }
    .mobile-bottom-nav .nav-items {
      display: flex;
      justify-content: space-around;
      align-items: center;
      height: 64px;
      padding: 0 8px;
    }
    .mobile-tab {
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      color: var(--color-text-muted);
      font-size: 12px;
      transition: color 0.2s;
      padding: 6px 4px;
    }
    .mobile-tab i {
      font-size: 20px;
      margin-bottom: 4px;
    }
    .mobile-tab.active {
      color: var(--color-accent);
    }

    /* 板块间距 */
    section {
      padding: 80px 0;
    }
    @media (max-width: 768px) {
      section {
        padding: 60px 0;
      }
    }

    /* H2 带序号风格 */
    .section-title {
      font-size: 32px;
      font-weight: 600;
      letter-spacing: -0.3px;
      color: var(--color-text-dark);
      margin-bottom: 16px;
    }
    .section-title .num {
      color: var(--color-accent);
      margin-right: 12px;
      font-weight: 700;
    }

    /* 数据看板数字 */
    .stat-number {
      font-size: 48px;
      font-weight: 700;
      color: var(--color-accent);
      line-height: 1.2;
    }

    /* FAQ 手风琴 */
    .faq-item {
      border-bottom: 1px solid var(--color-border);
    }
    .faq-question {
      font-size: 18px;
      font-weight: 600;
      padding: 20px 0;
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
      color: var(--color-text-dark);
      transition: color 0.2s;
    }
    .faq-question:hover {
      color: var(--color-accent);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease, padding 0.4s;
      color: var(--color-text-muted);
    }
    .faq-item.open .faq-answer {
      max-height: 200px;
      padding-bottom: 20px;
    }
    .faq-icon {
      font-size: 24px;
      font-weight: 300;
    }

    /* 表单输入 */
    .input-field {
      width: 100%;
      padding: 14px 16px;
      background: #F8FAFC;
      border: none;
      border-bottom: 1px solid var(--color-text-dark);
      border-radius: 4px 4px 0 0;
      outline: none;
      transition: border-color 0.2s, background 0.2s;
      font-size: 16px;
    }
    .input-field:focus {
      border-bottom-color: var(--color-accent);
      background: #FFFFFF;
    }

    /* 页脚 */
    footer {
      background-color: var(--color-text-dark);
      color: rgba(255,255,255,0.8);
      padding: 60px 0 30px;
    }
    footer a {
      color: rgba(255,255,255,0.7);
      transition: color 0.2s;
    }
    footer a:hover {
      color: var(--color-accent);
    }

    @media (max-width: 1023px) {
      .container {
        padding-left: 20px;
        padding-right: 20px;
      }
      .section-title {
        font-size: 28px;
      }
    }

    @media (max-width: 767px) {
      body {
        padding-bottom: 80px;
      }
      /* 显示底部导航，隐藏桌面导航 */
      .desktop-nav {
        display: none !important;
      }
      .mobile-bottom-nav {
        display: block;
      }
      .section-title {
        font-size: 26px;
      }
      .stat-number {
        font-size: 36px;
      }
      .hero-title {
        font-size: 32px !important;
      }
      .grid-cols-2, .grid-cols-3, .grid-cols-4 {
        grid-template-columns: 1fr !important;
      }
      .hero-flex {
        flex-direction: column;
      }
      .hero-text {
        text-align: center;
        margin-bottom: 32px;
      }
      .hero-image {
        width: 100%;
      }
    }
    @media (min-width: 768px) {
      .desktop-nav {
        display: flex !important;
      }
    }