/* roulang page: index */
:root {
      --primary: #4E6EF2;
      --primary-hover: #3D5CD9;
      --primary-soft: rgba(78,110,242,0.08);
      --green: #00B578;
      --orange: #FF9F0A;
      --red: #FA5151;
      --black: #1F2329;
      --gray: #86909C;
      --bg: #F5F6FA;
      --white: #FFFFFF;
      --border: #E5E8EF;
      --shadow: 0 2px 12px rgba(31,35,41,0.08);
      --shadow-hover: 0 4px 20px rgba(31,35,41,0.12);
      --radius: 12px;
      --radius-pill: 24px;
      --transition: 200ms ease-out;
    }

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

    body {
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      background: var(--bg);
      color: var(--black);
      line-height: 1.5;
      -webkit-font-smoothing: antialiased;
    }

    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 24px;
    }

    @media (max-width: 768px) {
      .container {
        padding: 0 16px;
      }
    }

    /* 导航 */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      right: 0;
      z-index: 100;
      background: var(--white);
      height: 64px;
      display: flex;
      align-items: center;
      box-shadow: 0 1px 4px rgba(0,0,0,0.04);
      transition: box-shadow var(--transition);
    }
    .header.scrolled {
      box-shadow: 0 2px 8px rgba(0,0,0,0.06);
    }
    .nav {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }
    .logo {
      font-size: 20px;
      font-weight: 700;
      color: var(--black);
      text-decoration: none;
      letter-spacing: -0.5px;
    }
    .logo span {
      color: var(--primary);
    }
    .nav-links {
      display: flex;
      gap: 28px;
      align-items: center;
    }
    .nav-links a {
      font-size: 14px;
      color: var(--gray);
      text-decoration: none;
      font-weight: 500;
      transition: color var(--transition);
      white-space: nowrap;
    }
    .nav-links a:hover {
      color: var(--primary);
    }
    .btn-primary {
      background: var(--primary);
      color: white;
      border: none;
      padding: 10px 24px;
      border-radius: var(--radius);
      font-weight: 600;
      font-size: 14px;
      cursor: pointer;
      transition: background var(--transition), transform 0.1s ease;
      text-decoration: none;
      display: inline-block;
      text-align: center;
      box-shadow: 0 2px 8px rgba(78,110,242,0.25);
    }
    .btn-primary:hover {
      background: var(--primary-hover);
      transform: translateY(-1px);
    }
    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--primary);
      color: var(--primary);
      padding: 10px 24px;
      border-radius: var(--radius);
      font-weight: 600;
      font-size: 14px;
      cursor: pointer;
      transition: all var(--transition);
      text-decoration: none;
      display: inline-block;
      text-align: center;
    }
    .btn-outline:hover {
      background: var(--primary-soft);
      border-color: var(--primary-hover);
      color: var(--primary-hover);
    }
    .btn-white {
      background: white;
      color: var(--primary);
      border: none;
      padding: 12px 28px;
      border-radius: var(--radius);
      font-weight: 700;
      font-size: 16px;
      box-shadow: var(--shadow);
    }
    .btn-white:hover {
      background: #f0f2ff;
      transform: translateY(-1px);
    }
    .hamburger {
      display: none;
      font-size: 22px;
      cursor: pointer;
      color: var(--black);
    }
    @media (max-width: 768px) {
      .nav-links {
        display: none;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        padding: 20px 24px;
        box-shadow: var(--shadow);
        gap: 16px;
      }
      .nav-links.active {
        display: flex;
      }
      .hamburger {
        display: block;
      }
    }

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

    /* Hero */
    .hero {
      background: var(--bg);
      padding-top: 120px;
      display: flex;
      align-items: center;
    }
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 48px;
      align-items: center;
    }
    .hero h1 {
      font-size: 36px;
      font-weight: 700;
      line-height: 1.3;
      margin-bottom: 16px;
    }
    .hero .sub {
      font-size: 16px;
      color: var(--gray);
      margin-bottom: 32px;
      max-width: 400px;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .hero-image {
      background: url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      border-radius: 24px;
      height: 320px;
      width: 100%;
      box-shadow: var(--shadow);
      position: relative;
      overflow: hidden;
    }
    @media (max-width: 768px) {
      .hero-grid {
        grid-template-columns: 1fr;
      }
      .hero-image {
        height: 240px;
      }
      .hero h1 {
        font-size: 30px;
      }
    }

    /* 标题 */
    h2 {
      font-size: 28px;
      font-weight: 600;
      margin-bottom: 16px;
      line-height: 1.4;
    }
    h3 {
      font-size: 20px;
      font-weight: 600;
      margin-bottom: 8px;
    }

    /* 卡片网格 */
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .grid-2 {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 24px;
    }
    @media (max-width: 1024px) {
      .grid-3, .grid-2 {
        grid-template-columns: repeat(2, 1fr);
      }
    }
    @media (max-width: 768px) {
      .grid-3, .grid-2 {
        grid-template-columns: 1fr;
      }
    }

    .card {
      background: var(--white);
      border-radius: var(--radius);
      padding: 24px;
      box-shadow: var(--shadow);
      transition: transform var(--transition), box-shadow var(--transition);
    }
    .card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
    }
    .icon-circle {
      width: 48px;
      height: 48px;
      background: var(--primary-soft);
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--primary);
      font-size: 22px;
      margin-bottom: 16px;
    }

    /* 功能交替 */
    .feature-row {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 48px;
      align-items: center;
      margin-bottom: 60px;
    }
    .feature-row.reverse {
      direction: rtl;
    }
    .feature-row.reverse > * {
      direction: ltr;
    }
    .feature-img {
      background: #e9ecf5;
      border-radius: 20px;
      height: 280px;
      background-size: cover;
      background-position: center;
      box-shadow: var(--shadow);
    }
    .feature-list {
      list-style: none;
      margin-top: 16px;
    }
    .feature-list li {
      display: flex;
      align-items: baseline;
      gap: 8px;
      font-size: 16px;
      margin-bottom: 8px;
      color: var(--black);
    }
    .feature-list li::before {
      content: '';
      width: 6px;
      height: 6px;
      background: var(--primary);
      border-radius: 50%;
      flex-shrink: 0;
      margin-top: 8px;
    }

    @media (max-width: 768px) {
      .feature-row {
        grid-template-columns: 1fr;
        gap: 24px;
      }
      .feature-img {
        height: 200px;
      }
    }

    .green-text {
      color: var(--green);
      font-weight: 500;
    }

    /* 数据卡片 */
    .stat-number {
      font-size: 36px;
      font-weight: 700;
      color: var(--primary);
    }

    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border);
      padding: 16px 0;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      font-weight: 600;
      font-size: 16px;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.25s ease;
      color: var(--gray);
      font-size: 14px;
      padding-right: 20px;
    }
    .faq-answer.open {
      max-height: 200px;
      padding-top: 12px;
    }

    /* CTA banner */
    .cta-banner {
      background: var(--primary);
      border-radius: 20px;
      padding: 48px;
      text-align: center;
      color: white;
    }
    .cta-banner h2 {
      color: white;
    }
    .cta-form {
      display: flex;
      gap: 12px;
      justify-content: center;
      margin-top: 24px;
      flex-wrap: wrap;
    }
    .cta-input {
      padding: 12px 20px;
      border-radius: 24px;
      border: 1px solid var(--border);
      background: white;
      min-width: 260px;
      font-size: 14px;
      outline: none;
      transition: 0.2s;
    }
    .cta-input:focus {
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgba(78,110,242,0.25);
    }

    footer {
      background: #1F2329;
      color: var(--gray);
      padding: 48px 0 24px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 30px;
      margin-bottom: 32px;
    }
    .footer-grid a {
      color: var(--gray);
      text-decoration: none;
      font-size: 14px;
      display: block;
      margin-bottom: 8px;
    }
    .footer-grid a:hover {
      color: white;
    }
    .copyright {
      font-size: 12px;
      border-top: 1px solid #2a2f38;
      padding-top: 20px;
      text-align: center;
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }

    .fade-up {
      opacity: 0;
      transform: translateY(20px);
      transition: opacity 0.5s ease, transform 0.5s ease;
    }
    .fade-up.visible {
      opacity: 1;
      transform: translateY(0);
    }