/* roulang page: index */
:root {
      --brand-deep: #0A2540;
      --brand-green: #00A86B;
      --brand-orange: #FF6B35;
      --brand-light: #F7F9FC;
      --brand-gray: #4A4A4A;
      --brand-body: #1A1A1A;
      --white: #FFFFFF;
      --radius-card: 16px;
      --radius-btn: 12px;
      --radius-block: 24px;
      --shadow-card: 0 4px 20px rgba(10,37,64,0.06);
      --shadow-hover: 0 12px 32px rgba(10,37,64,0.10);
    }
    * {
      box-sizing: border-box;
    }
    body {
      margin: 0;
      font-family: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
      color: var(--brand-body);
      background-color: var(--white);
      line-height: 1.75;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }
    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 20px;
    }
    h1, h2, h3, h4 {
      color: var(--brand-deep);
      margin: 0;
    }
    h1 {
      font-size: 40px;
      line-height: 1.2;
      font-weight: 700;
    }
    h2 {
      font-size: 32px;
      line-height: 1.25;
      font-weight: 600;
    }
    h3 {
      font-size: 20px;
      line-height: 1.4;
      font-weight: 500;
    }
    .section-padding {
      padding: 100px 0;
    }
    a {
      text-decoration: none;
      color: inherit;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    button, .btn {
      cursor: pointer;
      transition: all 0.25s ease;
    }
    /* 导航 */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(10px);
      z-index: 50;
      border-bottom: 1px solid rgba(10,37,64,0.05);
      transition: box-shadow 0.3s;
    }
    .header.scrolled {
      box-shadow: 0 4px 20px rgba(10,37,64,0.08);
    }
    .nav-link {
      font-weight: 500;
      color: var(--brand-body);
      position: relative;
      padding: 8px 0;
      transition: color 0.2s;
    }
    .nav-link:hover, .nav-link.active {
      color: var(--brand-green);
    }
    .nav-link::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 3px;
      background: var(--brand-green);
      border-radius: 4px;
      transition: width 0.3s;
    }
    .nav-link:hover::after, .nav-link.active::after {
      width: 100%;
    }
    /* 移动端底部导航 */
    .mobile-nav {
      display: none;
    }
    @media (max-width: 768px) {
      .desktop-nav {
        display: none;
      }
      .mobile-nav {
        display: flex;
        position: fixed;
        bottom: 16px;
        left: 50%;
        transform: translateX(-50%);
        width: calc(100% - 32px);
        max-width: 500px;
        background: white;
        box-shadow: 0 8px 28px rgba(10,37,64,0.15);
        border-radius: 24px;
        padding: 10px 16px;
        justify-content: space-around;
        z-index: 55;
      }
      .mobile-nav a {
        display: flex;
        flex-direction: column;
        align-items: center;
        font-size: 12px;
        color: var(--brand-gray);
        transition: 0.2s;
        font-weight: 500;
      }
      .mobile-nav a i {
        font-size: 18px;
        margin-bottom: 2px;
      }
      .mobile-nav a.active {
        color: var(--brand-green);
        font-weight: 600;
      }
      h1 {
        font-size: 32px;
        line-height: 1.3;
      }
      h2 {
        font-size: 26px;
      }
      .section-padding {
        padding: 70px 0;
      }
    }
    .btn-primary {
      background: var(--brand-green);
      color: white;
      border: none;
      padding: 14px 34px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 16px;
      display: inline-flex;
      align-items: center;
      gap: 8px;
      box-shadow: 0 4px 12px rgba(0,168,107,0.25);
    }
    .btn-primary:hover {
      background: #008F5A;
      box-shadow: 0 8px 20px rgba(0,143,90,0.35);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--brand-deep);
      color: var(--brand-deep);
      padding: 12px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
    }
    .btn-outline:hover {
      background: rgba(10,37,64,0.05);
    }
    .card {
      background: white;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      padding: 32px;
      transition: all 0.3s;
    }
    .card:hover {
      transform: translateY(-8px);
      box-shadow: var(--shadow-hover);
    }
    .accordion-btn {
      background: white;
      border: none;
      width: 100%;
      text-align: left;
      padding: 20px 24px;
      font-weight: 600;
      font-size: 18px;
      color: var(--brand-deep);
      display: flex;
      justify-content: space-between;
      align-items: center;
      border-radius: 12px;
      margin-bottom: 8px;
      transition: 0.2s;
    }
    .accordion-btn i {
      transition: transform 0.3s;
    }
    .accordion-content {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
      padding: 0 24px;
      color: var(--brand-gray);
    }
    .active-acc .accordion-content {
      max-height: 200px;
      padding-bottom: 16px;
    }
    .active-acc i {
      transform: rotate(45deg);
    }
    footer a:hover {
      text-decoration: underline;
      color: var(--brand-green);
    }