/* roulang page: index */
:root {
      --primary: #2563eb;
      --primary-dark: #1d4ed8;
      --accent: #0ea5e9;
      --bg-white: #ffffff;
      --bg-light: #f8fafc;
      --bg-cta: #f1f5f9;
      --text-heading: #0f172a;
      --text-body: #334155;
      --text-muted: #64748b;
      --text-white: #ffffff;
      --border: #e2e8f0;
      --border-dark: #cbd5e1;
      --shadow-card: 0 4px 12px rgba(0, 0, 0, 0.04);
      --shadow-card-hover: 0 8px 24px rgba(0, 0, 0, 0.08);
      --shadow-btn: 0 2px 4px rgba(0, 0, 0, 0.06);
      --shadow-btn-hover: 0 6px 16px rgba(37, 99, 235, 0.25);
      --radius-card: 1rem;
      --radius-btn: 0.5rem;
      --radius-input: 0.5rem;
      --container-max: 1280px;
      --font-sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
    }

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

    body {
      font-family: var(--font-sans);
      background-color: var(--bg-white);
      color: var(--text-body);
      line-height: 1.75;
      -webkit-font-smoothing: antialiased;
    }

    .container {
      max-width: var(--container-max);
      margin-left: auto;
      margin-right: auto;
      padding-left: 1.5rem;
      padding-right: 1.5rem;
    }

    h1, h2, h3 {
      color: var(--text-heading);
      font-weight: 700;
      line-height: 1.3;
    }

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

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

    button, .btn {
      cursor: pointer;
      border: none;
      background: none;
      font-family: inherit;
      font-size: inherit;
    }

    /* 导航 */
    .site-header {
      position: sticky;
      top: 0;
      z-index: 50;
      background: var(--bg-white);
      box-shadow: 0 1px 3px rgba(0,0,0,0.04);
      height: 64px;
      display: flex;
      align-items: center;
    }

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

    .logo {
      font-size: 1.5rem;
      font-weight: 800;
      color: var(--text-heading);
      letter-spacing: -0.5px;
    }
    .logo span {
      color: var(--primary);
    }

    .nav-links {
      display: flex;
      gap: 2rem;
      align-items: center;
    }
    .nav-links a {
      font-size: 0.95rem;
      font-weight: 500;
      color: #1e293b;
      padding-bottom: 4px;
      border-bottom: 2px solid transparent;
      transition: color 0.2s, border-color 0.2s;
    }
    .nav-links a:hover {
      color: var(--primary);
      border-bottom-color: var(--primary);
    }

    .hamburger {
      display: none;
      font-size: 1.5rem;
      color: var(--text-heading);
      background: none;
      border: none;
      cursor: pointer;
    }

    .mobile-menu {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: rgba(255,255,255,0.98);
      backdrop-filter: blur(4px);
      z-index: 100;
      flex-direction: column;
      align-items: flex-start;
      padding: 2rem 1.5rem;
      gap: 2rem;
    }
    .mobile-menu.active {
      display: flex;
    }
    .mobile-menu .close-btn {
      align-self: flex-end;
      font-size: 2rem;
      background: none;
      border: none;
      color: var(--text-heading);
    }
    .mobile-menu a {
      font-size: 1.25rem;
      font-weight: 500;
      color: #1e293b;
      border-bottom: 1px solid var(--border);
      width: 100%;
      padding-bottom: 0.75rem;
    }

    /* 公用板块 */
    section {
      padding: 5rem 0;
    }
    @media (max-width: 768px) {
      section {
        padding: 3rem 0;
      }
      .container {
        padding-left: 1rem;
        padding-right: 1rem;
      }
      .hamburger {
        display: block;
      }
      .nav-links {
        display: none;
      }
    }

    .section-title {
      font-size: 2rem;
      font-weight: 700;
      text-align: center;
      margin-bottom: 2.5rem;
      color: var(--text-heading);
    }
    @media (max-width: 768px) {
      .section-title {
        font-size: 1.5rem;
        margin-bottom: 2rem;
      }
    }

    /* 卡片 */
    .card {
      background: var(--bg-white);
      border-radius: var(--radius-card);
      padding: 1.5rem;
      box-shadow: var(--shadow-card);
      transition: box-shadow 0.3s ease;
    }
    .card:hover {
      box-shadow: var(--shadow-card-hover);
    }

    /* 按钮 */
    .btn-primary {
      background: var(--primary);
      color: white;
      padding: 0.75rem 1.5rem;
      border-radius: var(--radius-btn);
      font-weight: 600;
      display: inline-block;
      box-shadow: var(--shadow-btn);
      transition: all 0.2s ease;
      border: none;
      font-size: 1rem;
    }
    .btn-primary:hover {
      background: var(--primary-dark);
      box-shadow: var(--shadow-btn-hover);
      transform: translateY(-2px);
    }

    .btn-outline {
      background: transparent;
      border: 2px solid var(--primary);
      color: var(--primary);
      padding: 0.75rem 1.5rem;
      border-radius: var(--radius-btn);
      font-weight: 600;
      transition: all 0.2s ease;
      display: inline-block;
      font-size: 1rem;
    }
    .btn-outline:hover {
      background: var(--primary);
      color: white;
    }

    .btn-lg {
      padding: 0.75rem 2rem;
      font-size: 1.125rem;
    }

    /* 表单 */
    .input-field {
      width: 100%;
      padding: 0.75rem 1rem;
      border: 1px solid var(--border-dark);
      border-radius: var(--radius-input);
      color: var(--text-body);
      font-size: 1rem;
      transition: border 0.2s, box-shadow 0.2s;
      background: white;
    }
    .input-field:focus {
      outline: none;
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
    }

    /* Hero */
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 2.5rem;
    }
    .hero-text {
      flex: 1;
    }
    .hero-text h1 {
      font-size: 3rem;
      font-weight: 800;
      color: var(--text-heading);
      margin-bottom: 1rem;
    }
    .hero-text .subtitle {
      font-size: 1.25rem;
      color: var(--text-muted);
      margin-bottom: 2rem;
    }
    .hero-image {
      flex: 1;
    }
    .hero-image img {
      border-radius: 0.75rem;
      object-fit: cover;
      width: 100%;
      height: auto;
    }
    @media (max-width: 768px) {
      .hero-grid {
        flex-direction: column-reverse;
      }
      .hero-text h1 {
        font-size: 1.875rem;
      }
      .hero-text .subtitle {
        font-size: 1rem;
      }
    }

    /* 痛点卡片 */
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 1.5rem;
    }
    @media (max-width: 768px) {
      .grid-3 {
        grid-template-columns: 1fr;
      }
    }

    /* 优势2x2 */
    .grid-4 {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 1.5rem;
    }
    @media (max-width: 768px) {
      .grid-4 {
        grid-template-columns: 1fr;
      }
    }

    .feature-card {
      display: flex;
      gap: 1rem;
      align-items: flex-start;
      position: relative;
      border-left: 3px solid transparent;
      transition: border-color 0.2s;
    }
    .feature-card:hover {
      border-left-color: var(--primary);
    }
    .icon-circle {
      background: var(--primary);
      color: white;
      width: 48px;
      height: 48px;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 1.25rem;
      flex-shrink: 0;
    }

    /* 数据卡片 */
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 2rem;
      text-align: center;
    }
    .stat-item {
      border-bottom: 1px solid var(--border);
      padding-bottom: 1.5rem;
    }
    .stat-number {
      font-size: 3rem;
      font-weight: 800;
      color: var(--primary);
      line-height: 1.2;
    }
    @media (max-width: 768px) {
      .stats-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
      }
    }

    /* 证言 */
    .testimonial-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 1.5rem;
    }
    .testimonial-card {
      border-left: 4px solid var(--primary);
    }
    @media (max-width: 768px) {
      .testimonial-grid {
        grid-template-columns: 1fr;
      }
    }

    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border);
      padding: 1.25rem 0;
      cursor: pointer;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-weight: 600;
      color: var(--text-heading);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s;
      color: var(--text-muted);
      padding-top: 0;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-top: 0.75rem;
    }
    .faq-icon {
      transition: transform 0.2s;
    }
    .faq-item.active .faq-icon {
      transform: rotate(45deg);
    }

    /* CTA区域 */
    .cta-section {
      background: var(--bg-cta);
    }

    /* 页脚 */
    .site-footer {
      background: #1e293b;
      color: white;
      padding: 3rem 0 1.5rem;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr;
      gap: 2rem;
      margin-bottom: 2rem;
    }
    .footer-links a {
      display: block;
      color: #cbd5e1;
      margin-bottom: 0.5rem;
    }
    .footer-links a:hover {
      color: #60a5fa;
    }
    .copyright {
      text-align: center;
      color: #94a3b8;
      font-size: 0.9rem;
      border-top: 1px solid #334155;
      padding-top: 1.5rem;
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr;
      }
    }