/* roulang page: index */
:root {
      --primary-deep: #1A2B3C;
      --accent-cyan: #00C2BA;
      --highlight-orange: #FF6B35;
      --bg-light: #F8FAFC;
      --bg-white: #FFFFFF;
      --bg-subtle: #F1F5F9;
      --text-primary: #0F172A;
      --text-secondary: #475569;
      --text-muted: #94A3B8;
      --border-light: #E2E8F0;
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-tag: 4px;
      --shadow-sm: 0 1px 3px rgba(0,0,0,0.04), 0 1px 2px rgba(0,0,0,0.06);
      --shadow-hover: 0 10px 25px -5px rgba(0,0,0,0.08), 0 4px 10px -2px rgba(0,0,0,0.05);
      --font-sans: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Noto Sans SC", system-ui, -apple-system, sans-serif;
      --font-mono: "Inter", "SF Pro Display", system-ui, sans-serif;
      --transition: 0.2s ease;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    html {
      scroll-behavior: smooth;
      font-size: 16px;
    }
    body {
      font-family: var(--font-sans);
      background-color: var(--bg-white);
      color: var(--text-primary);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }
    .container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 32px;
    }
    h1, h2, h3, h4 {
      font-weight: 600;
      letter-spacing: -0.02em;
    }
    h1 {
      font-size: clamp(2.5rem, 7vw, 3.5rem);
      line-height: 1.15;
      font-weight: 700;
      color: var(--primary-deep);
    }
    h2 {
      font-size: clamp(2rem, 5vw, 2.5rem);
      line-height: 1.3;
      margin-bottom: 0.5rem;
    }
    h3 {
      font-size: 1.4rem;
      line-height: 1.4;
      font-weight: 600;
    }
    p {
      color: var(--text-secondary);
      font-size: 1rem;
    }
    a {
      text-decoration: none;
      color: inherit;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
      border-radius: var(--radius-card);
    }
    /* 导航 */
    .navbar {
      position: sticky;
      top: 0;
      z-index: 100;
      background: rgba(255,255,255,0.98);
      backdrop-filter: blur(8px);
      border-bottom: 1px solid var(--border-light);
      padding: 0 16px;
      height: 72px;
      display: flex;
      align-items: center;
      justify-content: space-between;
    }
    .logo {
      font-weight: 700;
      font-size: 1.8rem;
      color: var(--primary-deep);
      letter-spacing: -0.5px;
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .logo span {
      color: var(--accent-cyan);
      font-size: 2rem;
      margin-right: 4px;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
    }
    .nav-links a {
      font-weight: 500;
      color: var(--text-secondary);
      transition: color var(--transition);
      font-size: 0.95rem;
    }
    .nav-links a:hover {
      color: var(--accent-cyan);
    }
    .nav-cta {
      background: var(--accent-cyan);
      color: white !important;
      padding: 10px 24px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 0.9rem;
      transition: background var(--transition), transform 0.1s;
    }
    .nav-cta:hover {
      background: #00A8A2;
      transform: translateY(1px);
    }
    .menu-icon {
      display: none;
      background: none;
      border: none;
      font-size: 1.8rem;
      color: var(--primary-deep);
      cursor: pointer;
    }
    @media (max-width: 768px) {
      .nav-links {
        display: none;
        position: absolute;
        top: 72px;
        left: 0;
        width: 100%;
        background: white;
        flex-direction: column;
        padding: 32px 16px;
        border-bottom: 1px solid var(--border-light);
        gap: 24px;
        box-shadow: var(--shadow-sm);
      }
      .nav-links.active {
        display: flex;
      }
      .menu-icon {
        display: block;
      }
      .nav-cta {
        width: 100%;
        text-align: center;
        background: var(--accent-cyan);
      }
    }
    /* 按钮系统 */
    .btn-primary {
      background: var(--accent-cyan);
      border: none;
      color: #fff;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 1rem;
      display: inline-block;
      transition: background var(--transition), transform 0.1s;
      cursor: pointer;
      box-shadow: 0 2px 6px rgba(0,194,186,0.25);
    }
    .btn-primary:hover {
      background: #00A8A2;
      transform: translateY(1px);
    }
    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--primary-deep);
      color: var(--primary-deep);
      padding: 12px 28px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      transition: background 0.15s;
    }
    .btn-outline:hover {
      background: rgba(26,43,60,0.04);
    }
    .btn-text {
      color: var(--accent-cyan);
      font-weight: 600;
      padding: 4px 0;
      border-bottom: 2px solid transparent;
      transition: border-color 0.2s;
    }
    .btn-text:hover {
      border-bottom: 2px solid var(--accent-cyan);
    }
    section {
      padding: 100px 0;
    }
    @media (max-width: 768px) {
      section {
        padding: 80px 0;
      }
      .container {
        padding: 0 20px;
      }
    }
    /* 英雄区 */
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 40px;
      align-items: center;
      min-height: 70vh;
    }
    .hero-content {
      max-width: 600px;
    }
    .hero-content p {
      font-size: 1.25rem;
      margin: 24px 0 32px;
      line-height: 1.6;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .hero-visual {
      background: #E2E8F0;
      border-radius: 24px;
      overflow: hidden;
      box-shadow: var(--shadow-hover);
    }
    @media (max-width: 768px) {
      .hero-grid {
        grid-template-columns: 1fr;
        text-align: center;
      }
      .hero-content {
        margin: 0 auto;
      }
      .hero-buttons {
        justify-content: center;
      }
      .hero-visual {
        order: -1;
        max-height: 300px;
      }
    }
    /* 卡片通用 */
    .card {
      background: var(--bg-white);
      border-radius: var(--radius-card);
      padding: 32px;
      box-shadow: var(--shadow-sm);
      transition: box-shadow 0.2s, transform 0.2s;
    }
    .card:hover {
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
    }
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 28px;
      margin-top: 48px;
    }
    .stat-number {
      font-family: var(--font-mono);
      font-weight: 700;
      font-size: 2.5rem;
      color: var(--accent-cyan);
    }
    /* 图文交错 */
    .feature-row {
      display: flex;
      align-items: center;
      gap: 60px;
      margin: 60px 0;
    }
    .feature-text {
      flex: 1;
    }
    .feature-img {
      flex: 1;
      background: #E2E8F0;
      border-radius: 20px;
      min-height: 320px;
      display: flex;
      align-items: center;
      justify-content: center;
      background-size: cover;
    }
    .reverse {
      flex-direction: row-reverse;
    }
    @media (max-width: 768px) {
      .feature-row, .reverse {
        flex-direction: column;
        gap: 28px;
      }
      .grid-3 {
        grid-template-columns: 1fr;
      }
      .feature-img {
        width: 100%;
        min-height: 220px;
      }
    }
    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }
    .faq-question {
      background: transparent;
      border: none;
      width: 100%;
      text-align: left;
      padding: 24px 8px;
      font-weight: 600;
      font-size: 1.1rem;
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      color: var(--text-primary);
    }
    .faq-answer {
      padding: 0 8px 24px;
      color: var(--text-secondary);
      display: none;
    }
    .faq-item.active .faq-answer {
      display: block;
    }
    .faq-item.active .faq-question {
      color: var(--accent-cyan);
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 30px;
      padding: 60px 0 30px;
      border-top: 1px solid var(--border-light);
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }
    .footer-bottom {
      text-align: center;
      padding: 20px 0;
      color: var(--text-muted);
      font-size: 0.85rem;
    }