/* roulang page: index */
:root {
      --primary: #1A5FDC;
      --primary-dark: #0F3D9E;
      --accent: #FF6B35;
      --accent-hover: #E55A2B;
      --bg-light: #F6F9FF;
      --white: #FFFFFF;
      --text-dark: #1B1B2F;
      --text-mid: #5A6070;
      --text-light: #8E94A0;
      --border-light: #E8ECF1;
      --shadow-card: 0 8px 28px rgba(26, 95, 220, 0.06);
      --shadow-hover: 0 14px 36px rgba(26, 95, 220, 0.12);
      --radius-card: 16px;
      --radius-btn: 8px;
      --font-sans: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', Arial, sans-serif;
      --max-width: 1200px;
      --nav-height: 72px;
    }

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

    body {
      font-family: var(--font-sans);
      background: var(--white);
      color: var(--text-mid);
      line-height: 1.5;
      -webkit-font-smoothing: antialiased;
    }

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

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

    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }

    /* 导航 */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      background: rgba(255, 255, 255, 0.92);
      backdrop-filter: blur(12px);
      box-shadow: 0 2px 12px rgba(0,0,0,0.02);
      z-index: 1000;
      display: flex;
      align-items: center;
    }

    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }

    .logo {
      font-size: 24px;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: 0.5px;
      white-space: nowrap;
    }

    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
    }

    .nav-links a {
      font-size: 15px;
      font-weight: 500;
      color: var(--text-mid);
      padding: 8px 0;
      position: relative;
      transition: color 0.2s;
    }

    .nav-links a:hover,
    .nav-links a.active {
      color: var(--primary);
    }

    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--primary);
      transition: width 0.25s ease;
    }

    .nav-links a:hover::after,
    .nav-links a.active::after {
      width: 100%;
    }

    .btn-nav {
      background: var(--accent);
      color: white !important;
      padding: 10px 22px !important;
      border-radius: var(--radius-btn);
      font-weight: 600;
      box-shadow: 0 4px 12px rgba(255,107,53,0.25);
      transition: background 0.2s, transform 0.2s;
      margin-left: 12px;
      white-space: nowrap;
    }

    .btn-nav:hover {
      background: var(--accent-hover);
      transform: translateY(-1px);
    }

    .menu-toggle {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: transparent;
      border: none;
      padding: 8px;
    }

    .menu-toggle span {
      display: block;
      width: 26px;
      height: 2.5px;
      background: var(--text-dark);
      border-radius: 2px;
      transition: 0.2s;
    }

    @media (max-width: 1024px) {
      .nav-links {
        gap: 20px;
      }
    }

    @media (max-width: 768px) {
      .menu-toggle {
        display: flex;
        z-index: 1001;
      }
      .nav-links {
        position: fixed;
        top: 0;
        right: 0;
        width: 80%;
        max-width: 320px;
        height: 100vh;
        background: white;
        flex-direction: column;
        align-items: flex-start;
        padding: 100px 32px 40px;
        gap: 28px;
        box-shadow: -8px 0 30px rgba(0,0,0,0.08);
        transform: translateX(100%);
        transition: transform 0.3s ease;
      }
      .nav-links.active {
        transform: translateX(0);
      }
      .nav-links a {
        font-size: 18px;
      }
      .btn-nav {
        margin-left: 0;
        width: 100%;
        text-align: center;
      }
    }

    /* 通用板块 */
    section {
      padding: 90px 0;
    }

    .section-title {
      font-size: 28px;
      font-weight: 700;
      color: var(--text-dark);
      margin-bottom: 16px;
      letter-spacing: 0.02em;
    }

    .section-sub {
      font-size: 16px;
      color: var(--text-light);
      margin-bottom: 48px;
    }

    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 28px;
    }

    .grid-2 {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 28px;
    }

    .card {
      background: var(--white);
      border-radius: var(--radius-card);
      padding: 32px 28px;
      box-shadow: var(--shadow-card);
      transition: all 0.25s ease;
      border: 1px solid rgba(26,95,220,0.04);
    }

    .card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-hover);
    }

    .btn {
      display: inline-block;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 15px;
      transition: all 0.2s ease;
      cursor: pointer;
      border: none;
    }

    .btn-primary {
      background: var(--accent);
      color: white;
      box-shadow: 0 6px 18px rgba(255,107,53,0.3);
    }

    .btn-primary:hover {
      background: var(--accent-hover);
      transform: translateY(-2px);
    }

    .btn-secondary {
      background: transparent;
      border: 2px solid var(--primary);
      color: var(--primary);
    }

    .btn-secondary:hover {
      background: var(--primary);
      color: white;
    }

    @media (max-width: 768px) {
      section {
        padding: 60px 0;
      }
      .grid-3, .grid-2 {
        grid-template-columns: 1fr;
        gap: 20px;
      }
      .section-title {
        font-size: 24px;
      }
    }