/* roulang page: index */
:root {
      --primary: #E8453C;
      --primary-hover: #D03A32;
      --secondary: #2B5AED;
      --secondary-light: rgba(43, 90, 237, 0.08);
      --bg: #F5F6FA;
      --white: #FFFFFF;
      --dark: #1F2329;
      --dark-bg: #1F2329;
      --text: #1F2329;
      --text-secondary: #86909C;
      --border: #E5E8EF;
      --success: #00B578;
      --warning: #FF9F0A;
      --error: #FA5151;
      --shadow-sm: 0 2px 12px rgba(0,0,0,0.04);
      --shadow-md: 0 4px 20px rgba(0,0,0,0.08);
      --radius: 12px;
      --max-width: 1200px;
      --nav-height: 64px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    body {
      font-family: system-ui, -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      background-color: var(--bg);
      color: var(--text);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }
    img {
      max-width: 100%;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color 0.2s;
    }
    button {
      font-family: inherit;
      cursor: pointer;
      border: none;
      background: none;
    }
    h1, h2, h3 {
      font-weight: 600;
    }
    .section {
      padding: 100px 0;
    }
    @media (max-width: 768px) {
      .section {
        padding: 60px 0;
      }
      .container {
        padding: 0 16px;
      }
    }

    /* 导航 */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      background: var(--white);
      border-bottom: 1px solid var(--border);
      z-index: 1000;
      transition: box-shadow 0.3s;
    }
    .header.scrolled {
      box-shadow: 0 2px 8px rgba(0,0,0,0.04);
    }
    .nav {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 100%;
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }
    .logo {
      font-size: 22px;
      font-weight: 700;
      color: var(--primary);
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .logo i {
      font-size: 24px;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
      list-style: none;
    }
    .nav-links a {
      font-size: 15px;
      color: var(--text);
      font-weight: 500;
      padding: 8px 0;
      border-bottom: 2px solid transparent;
      transition: 0.2s;
    }
    .nav-links a:hover,
    .nav-links a.active {
      color: var(--primary);
      border-bottom-color: var(--primary);
    }
    .nav-cta {
      background: var(--primary);
      color: white !important;
      padding: 10px 24px !important;
      border-radius: var(--radius);
      font-weight: 600;
      transition: 0.2s;
      border-bottom: none !important;
    }
    .nav-cta:hover {
      background: var(--primary-hover);
      transform: translateY(-1px);
    }
    .mobile-toggle {
      display: none;
      font-size: 24px;
      color: var(--text);
    }
    @media (max-width: 768px) {
      .nav-links {
        display: none;
        position: fixed;
        top: var(--nav-height);
        left: 0;
        width: 100%;
        background: white;
        flex-direction: column;
        padding: 24px;
        gap: 20px;
        box-shadow: var(--shadow-md);
      }
      .nav-links.open {
        display: flex;
      }
      .mobile-toggle {
        display: block;
      }
      .nav-cta {
        width: 100%;
        text-align: center;
      }
    }

    /* Hero */
    .hero {
      padding: 120px 0 80px;
      background: var(--white);
      border-bottom: 1px solid var(--border);
    }
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 60px;
    }
    .hero-text {
      flex: 1;
    }
    .hero-text h1 {
      font-size: 40px;
      font-weight: 700;
      line-height: 1.3;
      color: var(--text);
      margin-bottom: 20px;
    }
    .hero-text h1 span {
      color: var(--primary);
    }
    .hero-text p {
      font-size: 18px;
      color: var(--text-secondary);
      margin-bottom: 32px;
      line-height: 1.6;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 12px 28px;
      border-radius: var(--radius);
      font-weight: 600;
      font-size: 16px;
      transition: 0.25s;
      min-height: 48px;
    }
    .btn-primary {
      background: var(--primary);
      color: white;
    }
    .btn-primary:hover {
      background: var(--primary-hover);
      transform: translateY(-2px);
      box-shadow: var(--shadow-md);
    }
    .btn-secondary {
      background: transparent;
      border: 1.5px solid var(--secondary);
      color: var(--secondary);
    }
    .btn-secondary:hover {
      background: var(--secondary-light);
    }
    .hero-image {
      flex: 1;
      border-radius: var(--radius);
      overflow: hidden;
      box-shadow: var(--shadow-md);
    }
    .hero-image img {
      width: 100%;
      height: auto;
    }
    @media (max-width: 768px) {
      .hero-grid {
        flex-direction: column-reverse;
        gap: 40px;
      }
      .hero-text h1 {
        font-size: 32px;
      }
      .hero-text p {
        font-size: 16px;
      }
    }

    /* 卡片通用 */
    .card {
      background: var(--white);
      border-radius: var(--radius);
      padding: 32px 24px;
      box-shadow: var(--shadow-sm);
      transition: 0.25s;
      height: 100%;
      display: flex;
      flex-direction: column;
    }
    .card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-md);
    }
    .icon-circle {
      width: 56px;
      height: 56px;
      background: var(--secondary-light);
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      margin-bottom: 20px;
      color: var(--secondary);
      font-size: 24px;
    }

    /* 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;
    }
    .grid-4 {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
    }
    @media (max-width: 992px) {
      .grid-3, .grid-4 {
        grid-template-columns: repeat(2, 1fr);
      }
    }
    @media (max-width: 768px) {
      .grid-3, .grid-2, .grid-4 {
        grid-template-columns: 1fr;
      }
    }

    .section-title {
      text-align: center;
      margin-bottom: 56px;
    }
    .section-title h2 {
      font-size: 32px;
      color: var(--text);
      margin-bottom: 12px;
    }
    .section-title p {
      color: var(--text-secondary);
      font-size: 16px;
    }

    /* 功能切换 */
    .features-block {
      background: var(--bg);
    }
    .feature-interactive {
      display: flex;
      gap: 40px;
      align-items: flex-start;
    }
    .feature-tabs {
      display: flex;
      flex-direction: column;
      gap: 8px;
      min-width: 200px;
    }
    .feature-tab {
      padding: 14px 20px;
      font-weight: 500;
      color: var(--text-secondary);
      border-left: 4px solid transparent;
      cursor: pointer;
      transition: 0.2s;
      background: transparent;
      text-align: left;
      font-size: 16px;
    }
    .feature-tab.active {
      color: var(--text);
      font-weight: 600;
      border-left-color: var(--primary);
      background: rgba(232,69,60,0.04);
    }
    .feature-content {
      flex: 1;
      background: white;
      border-radius: var(--radius);
      padding: 32px;
      box-shadow: var(--shadow-sm);
      display: flex;
      gap: 24px;
      align-items: center;
    }
    .feature-content img {
      width: 45%;
      border-radius: var(--radius);
    }
    @media (max-width: 768px) {
      .feature-interactive {
        flex-direction: column;
      }
      .feature-tabs {
        flex-direction: row;
        overflow-x: auto;
        min-width: auto;
      }
      .feature-tab {
        border-left: none;
        border-bottom: 3px solid transparent;
        white-space: nowrap;
      }
      .feature-tab.active {
        border-bottom-color: var(--primary);
        border-left: none;
      }
      .feature-content {
        flex-direction: column;
      }
      .feature-content img {
        width: 100%;
      }
    }

    /* 深色案例 */
    .cases-bg {
      background: var(--dark-bg);
      color: white;
    }
    .cases-bg .section-title h2,
    .cases-bg .section-title p {
      color: white;
    }
    .metric-number {
      font-size: 36px;
      font-weight: 700;
      color: var(--secondary);
    }
    .case-card {
      background: rgba(255,255,255,0.08);
      border-radius: var(--radius);
      padding: 28px;
    }
    .case-quote {
      font-style: italic;
      font-size: 16px;
      margin: 16px 0;
    }
    .success-highlight {
      color: var(--success);
      font-weight: 600;
    }

    /* 价格 */
    .pricing-card {
      text-align: center;
      position: relative;
    }
    .pricing-card.popular {
      border: 2px solid var(--primary);
      transform: scale(1.03);
    }
    .popular-badge {
      background: var(--primary);
      color: white;
      font-size: 12px;
      padding: 4px 12px;
      border-radius: 20px;
      position: absolute;
      top: -12px;
      left: 50%;
      transform: translateX(-50%);
    }
    .price {
      font-size: 36px;
      font-weight: 700;
      margin: 16px 0;
    }

    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border);
      padding: 20px 0;
    }
    .faq-question {
      display: flex;
      align-items: center;
      gap: 12px;
      font-weight: 600;
      cursor: pointer;
      font-size: 16px;
    }
    .faq-answer {
      color: var(--text-secondary);
      font-size: 14px;
      margin-top: 12px;
      display: none;
      padding-left: 28px;
    }
    .faq-item.open .faq-answer {
      display: block;
    }

    /* CTA */
    .cta-block {
      background: var(--dark-bg);
      text-align: center;
      color: white;
    }
    .cta-block h2 {
      font-size: 32px;
      margin-bottom: 12px;
    }

    /* Footer */
    .footer {
      background: var(--dark-bg);
      color: var(--text-secondary);
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
    }
    .footer a:hover {
      color: var(--primary);
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }
    .copyright {
      border-top: 1px solid #333;
      margin-top: 40px;
      padding-top: 20px;
      text-align: center;
      font-size: 12px;
    }