/* roulang page: index */
:root {
      --primary: #1A5F7A;
      --primary-hover: #134B61;
      --accent: #0D9488;
      --accent-light: rgba(13, 148, 136, 0.10);
      --bg: #F8FAFC;
      --surface: #FFFFFF;
      --surface-alt: #EFF6F9;
      --text: #1E293B;
      --text-soft: #475569;
      --text-muted: #64748B;
      --border: #E2E8F0;
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-tag: 20px;
      --shadow-sm: 0 1px 3px rgba(0,0,0,0.04), 0 4px 12px rgba(0,0,0,0.04);
      --shadow-hover: 0 6px 20px rgba(26,95,122,0.10);
      --font-sans: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Noto Sans SC", sans-serif;
      --nav-height: 64px;
    }
    * { margin: 0; padding: 0; box-sizing: border-box; }
    html { scroll-behavior: smooth; }
    body {
      font-family: var(--font-sans);
      background: var(--bg);
      color: var(--text);
      line-height: 1.8;
      font-size: 16px;
      font-weight: 400;
    }
    img { max-width: 100%; height: auto; display: block; }
    a { text-decoration: none; color: inherit; }
    button, .btn { cursor: pointer; font-family: inherit; }
    .container {
      max-width: 1200px;
      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(8px);
      -webkit-backdrop-filter: blur(8px);
      box-shadow: 0 1px 0 var(--border);
      z-index: 50;
      display: flex;
      align-items: center;
      transition: 0.2s;
    }
    .nav {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
    }
    .logo {
      font-size: 1.5rem;
      font-weight: 700;
      color: var(--primary);
      display: flex;
      align-items: baseline;
      gap: 4px;
      white-space: nowrap;
    }
    .logo span {
      font-size: 0.8rem;
      font-weight: 400;
      color: var(--text-muted);
      margin-left: 4px;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
    }
    .nav-links a {
      font-weight: 500;
      font-size: 0.95rem;
      color: var(--text-soft);
      transition: color 0.2s;
      position: relative;
    }
    .nav-links a:hover,
    .nav-links a.active {
      color: var(--primary);
    }
    .btn-primary {
      background: var(--primary);
      color: white;
      padding: 10px 20px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 0.9rem;
      border: none;
      transition: 0.2s ease;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      box-shadow: 0 2px 8px rgba(26,95,122,0.2);
    }
    .btn-primary:hover {
      background: var(--primary-hover);
      transform: translateY(-2px);
      box-shadow: 0 8px 18px rgba(26,95,122,0.25);
    }
    .btn-outline {
      background: transparent;
      border: 1px solid var(--primary);
      color: var(--primary);
      padding: 10px 20px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 0.9rem;
      transition: 0.2s;
    }
    .btn-outline:hover {
      background: rgba(26,95,122,0.08);
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      background: none;
      border: none;
    }
    .hamburger span {
      width: 24px;
      height: 2px;
      background: var(--primary);
      border-radius: 2px;
      transition: 0.2s;
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: white;
      z-index: 60;
      flex-direction: column;
      padding: 24px;
      opacity: 0;
      pointer-events: none;
      transition: opacity 0.3s;
    }
    .mobile-menu.open {
      display: flex;
      opacity: 1;
      pointer-events: auto;
    }
    .mobile-menu .close-btn {
      align-self: flex-end;
      font-size: 2rem;
      background: none;
      border: none;
      color: var(--text);
    }
    .mobile-menu a {
      font-size: 1.3rem;
      padding: 16px 0;
      border-bottom: 1px solid var(--border);
      color: var(--text);
    }

    /* 版块间距 */
    section {
      padding: 80px 0;
    }
    .section-title {
      font-size: 32px;
      font-weight: 700;
      letter-spacing: -0.3px;
      color: var(--text);
      margin-bottom: 16px;
    }
    .section-sub {
      font-size: 18px;
      color: var(--text-soft);
      margin-bottom: 48px;
    }

    /* Hero */
    .hero {
      padding-top: calc(var(--nav-height) + 40px);
      display: flex;
      align-items: center;
      gap: 60px;
    }
    .hero-left {
      flex: 1;
    }
    .hero-left h1 {
      font-size: 48px;
      font-weight: 700;
      letter-spacing: -0.5px;
      line-height: 1.2;
      margin-bottom: 20px;
    }
    .hero-left .sub {
      font-size: 18px;
      color: var(--text-soft);
      margin-bottom: 32px;
      max-width: 450px;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .hero-right {
      flex: 1;
      display: flex;
      justify-content: center;
    }
    .hero-right img {
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
      width: 100%;
      height: auto;
      object-fit: cover;
      background: #e2e8f0;
    }

    /* 亮点网格 */
    .features-grid {
      display: grid;
      grid-template-columns: 1fr 1fr 1fr;
      gap: 24px;
      margin-top: 32px;
    }
    .feature-card {
      background: var(--surface);
      border-radius: var(--radius-card);
      padding: 28px;
      box-shadow: var(--shadow-sm);
      transition: 0.25s ease;
    }
    .feature-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
    }
    .feature-icon {
      width: 48px;
      height: 48px;
      background: rgba(13,148,136,0.1);
      border-radius: 12px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--accent);
      font-size: 24px;
      margin-bottom: 20px;
    }
    .feature-card h3 {
      font-size: 20px;
      font-weight: 600;
      margin-bottom: 10px;
    }
    .feature-card p {
      color: var(--text-muted);
      font-size: 15px;
    }
    .row-variant {
      display: grid;
      grid-template-columns: 1.5fr 1fr 0.5fr;
      gap: 24px;
      margin-top: 24px;
    }

    /* 案例瀑布流 */
    .masonry {
      columns: 3;
      column-gap: 24px;
      margin-top: 40px;
    }
    .case-card {
      background: var(--surface);
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      margin-bottom: 24px;
      break-inside: avoid;
      transition: 0.25s;
    }
    .case-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
    }
    .case-card img {
      width: 100%;
      aspect-ratio: 16/9;
      object-fit: cover;
      transition: transform 0.3s;
    }
    .case-card:hover img {
      transform: scale(1.03);
    }
    .case-content {
      padding: 16px;
    }
    .case-content h3 {
      font-size: 18px;
      font-weight: 600;
      margin-bottom: 8px;
    }
    .tag {
      display: inline-block;
      background: rgba(13,148,136,0.1);
      color: var(--accent);
      padding: 4px 12px;
      border-radius: 20px;
      font-size: 13px;
      font-weight: 500;
    }

    /* 对比区 */
    .compare-row {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 24px;
      margin-top: 40px;
    }
    .compare-col {
      padding: 32px;
      border-radius: var(--radius-card);
    }
    .compare-left {
      background: #FEF2F2;
    }
    .compare-right {
      background: #F0FDF4;
    }
    .compare-col h3 {
      font-size: 22px;
      margin-bottom: 24px;
    }
    .compare-item {
      display: flex;
      align-items: center;
      gap: 12px;
      margin-bottom: 16px;
      font-size: 16px;
    }

    /* FAQ */
    .faq-list {
      max-width: 720px;
      margin: 40px auto 0;
    }
    .faq-item {
      border-bottom: 1px solid var(--border);
      padding: 18px 0;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-size: 20px;
      font-weight: 600;
      cursor: pointer;
      background: none;
      border: none;
      width: 100%;
      text-align: left;
      color: var(--text);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease;
      color: var(--text-soft);
      background: #F8FAFC;
      padding: 0 8px;
      border-radius: 8px;
    }
    .faq-item.open .faq-answer {
      max-height: 200px;
      padding: 12px 8px;
      margin-top: 8px;
    }
    .arrow {
      transition: transform 0.3s;
      font-size: 18px;
    }
    .faq-item.open .arrow {
      transform: rotate(180deg);
    }

    /* CTA */
    .cta-band {
      background: linear-gradient(105deg, rgba(26,95,122,0.06) 0%, rgba(13,148,136,0.08) 100%);
      text-align: center;
      padding: 70px 24px;
      border-radius: 32px;
      margin: 60px 0;
    }

    /* 页脚 */
    .footer {
      background: #0F172A;
      color: #CBD5E1;
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 1.5fr 1fr 1fr 1fr;
      gap: 40px;
    }
    .footer a {
      color: #94A3B8;
      transition: color 0.2s;
    }
    .footer a:hover { color: white; }
    .footer-bottom {
      border-top: 1px solid #1E293B;
      margin-top: 40px;
      padding-top: 24px;
      text-align: center;
      font-size: 14px;
      color: #64748B;
    }

    @media (max-width: 1024px) {
      .hero { gap: 32px; }
      .hero-left h1 { font-size: 38px; }
    }
    @media (max-width: 768px) {
      .nav-links, .header .btn-primary { display: none; }
      .hamburger { display: flex; }
      .hero {
        flex-direction: column;
        text-align: center;
      }
      .hero-right img { height: 240px; object-fit: cover; }
      .features-grid, .row-variant {
        grid-template-columns: 1fr;
      }
      .masonry { columns: 2; }
      .compare-row { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr; }
      section { padding: 50px 0; }
    }
    @media (max-width: 520px) {
      .masonry { columns: 1; }
      .hero-left h1 { font-size: 32px; }
    }