/* roulang page: index */
/* ----- 设计变量 ----- */
    :root {
      --primary: #1A1A2E;
      --primary-soft: rgba(26, 26, 46, 0.05);
      --accent: #E94560;
      --accent-hover: #C81E45;
      --accent-soft: rgba(233, 69, 96, 0.08);
      --bg-light: #F8F9FA;
      --bg-dark: #16213E;
      --bg-footer: #1A1A2E;
      --white: #FFFFFF;
      --text-primary: #1A1A2E;
      --text-secondary: #5A5A6E;
      --text-on-dark: #FFFFFF;
      --text-muted-on-dark: #CCCCD5;
      --border-light: #E0E0E5;
      --border-soft: rgba(0,0,0,0.04);
      --shadow-card: 0 4px 12px rgba(0,0,0,0.04);
      --shadow-card-hover: 0 8px 24px rgba(0,0,0,0.08);
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-input: 6px;
      --font-family: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Noto Sans SC", sans-serif;
      --max-width: 1200px;
      --section-gap: 120px;
      --card-padding: 32px;
      --grid-gutter: 32px;
      --transition-fast: 0.2s ease;
      --transition-smooth: 0.3s ease;
    }

    /* ----- reset & base ----- */
    *, *::before, *::after {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    html {
      scroll-behavior: smooth;
    }
    body {
      font-family: var(--font-family);
      font-size: 16px;
      line-height: 1.6;
      background-color: var(--bg-light);
      color: var(--text-primary);
      -webkit-font-smoothing: antialiased;
      text-rendering: optimizeLegibility;
    }
    img {
      display: block;
      max-width: 100%;
      height: auto;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color var(--transition-fast);
    }
    button, input {
      font-family: inherit;
      font-size: inherit;
    }
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }
    h1, h2, h3 {
      letter-spacing: -0.02em;
    }
    h1 {
      font-size: 48px;
      line-height: 56px;
      font-weight: 800;
      color: var(--text-primary);
    }
    h2 {
      font-size: 36px;
      line-height: 44px;
      font-weight: 700;
      color: var(--text-primary);
      margin-bottom: 16px;
    }
    h3 {
      font-size: 22px;
      line-height: 30px;
      font-weight: 600;
      color: var(--text-primary);
    }
    p, .text-body {
      font-size: 16px;
      line-height: 28px;
      font-weight: 400;
      color: var(--text-secondary);
      max-width: 72ch;
    }
    .text-small {
      font-size: 14px;
      line-height: 22px;
      color: var(--text-secondary);
    }

    /* ----- 导航栏：极简高端文字导航 ----- */
    .site-header {
      position: sticky;
      top: 0;
      z-index: 50;
      background: var(--white);
      border-bottom: 1px solid var(--border-light);
      height: 72px;
      display: flex;
      align-items: center;
    }
    .header-inner {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }
    .logo {
      font-size: 24px;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: -0.02em;
      white-space: nowrap;
    }
    .nav-links {
      display: flex;
      gap: 40px;
      align-items: center;
    }
    .nav-links a {
      font-size: 16px;
      font-weight: 500;
      color: var(--text-secondary);
      padding: 8px 0;
      position: relative;
      transition: color var(--transition-fast);
    }
    .nav-links a:hover,
    .nav-links a.active {
      color: var(--primary);
    }
    .nav-links a.active::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 100%;
      height: 2px;
      background: var(--accent);
      border-radius: 2px;
    }
    .menu-toggle {
      display: none;
      background: none;
      border: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      padding: 8px;
    }
    .menu-toggle span {
      display: block;
      width: 24px;
      height: 1.5px;
      background: var(--primary);
      transition: var(--transition-fast);
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: 72px;
      left: 0;
      width: 100%;
      background: var(--white);
      box-shadow: var(--shadow-card);
      flex-direction: column;
      padding: 24px;
      gap: 24px;
      z-index: 40;
    }
    .mobile-menu a {
      font-size: 18px;
      font-weight: 500;
      color: var(--text-primary);
      padding: 12px 0;
      border-bottom: 1px solid var(--border-light);
    }

    /* ----- 区块间距与通用背景 ----- */
    .section {
      padding: var(--section-gap) 0;
    }
    .bg-light-gray {
      background-color: var(--bg-light);
    }
    .bg-white {
      background-color: var(--white);
    }
    .bg-dark {
      background-color: var(--bg-dark);
      color: var(--text-on-dark);
    }

    /* ----- 按钮 ----- */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      height: 48px;
      padding: 0 24px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 16px;
      transition: all var(--transition-fast);
      cursor: pointer;
      border: none;
      background: transparent;
      white-space: nowrap;
    }
    .btn-primary {
      background: var(--accent);
      color: var(--white);
    }
    .btn-primary:hover {
      background: var(--accent-hover);
    }
    .btn-outline {
      border: 1px solid var(--primary);
      color: var(--primary);
      background: transparent;
    }
    .btn-outline:hover {
      background: rgba(26, 26, 46, 0.08);
    }
    .btn-white {
      background: var(--white);
      color: var(--primary);
      border: 1px solid var(--border-light);
    }
    .btn-white:hover {
      background: var(--bg-light);
    }

    /* ----- 卡片基础 ----- */
    .card {
      background: var(--white);
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      transition: box-shadow var(--transition-smooth), transform var(--transition-smooth);
      overflow: hidden;
    }
    .card:hover {
      box-shadow: var(--shadow-card-hover);
    }

    /* ----- Hero 首屏 ----- */
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      min-height: 90vh;
      align-items: center;
      gap: 60px;
    }
    .hero-left {
      display: flex;
      flex-direction: column;
      gap: 24px;
      align-items: flex-start;
    }
    .hero-subtitle {
      font-size: 18px;
      line-height: 30px;
      color: var(--text-secondary);
      max-width: 480px;
    }
    .hero-image {
      width: 100%;
      height: 100%;
      border-radius: 16px;
      object-fit: cover;
      box-shadow: 0 12px 36px rgba(0,0,0,0.08);
      background: var(--primary-soft);
      position: relative;
      z-index: 2;
    }
    .hero-visual {
      position: relative;
      display: flex;
      align-items: center;
      justify-content: center;
    }
    .hero-visual::before {
      content: '';
      position: absolute;
      top: 20px;
      left: 20px;
      width: 100%;
      height: 100%;
      background-image: radial-gradient(circle at 20% 30%, rgba(26,26,46,0.08) 1px, transparent 1px);
      background-size: 24px 24px;
      z-index: 1;
      border-radius: 16px;
    }

    /* ----- 亮点网格（无卡片轻量） ----- */
    .highlights-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: var(--grid-gutter);
      text-align: center;
    }
    .highlight-item {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 16px;
      padding: 24px 20px;
    }
    .highlight-icon {
      font-size: 48px;
      color: var(--accent);
      line-height: 1;
    }

    /* ----- 案例瀑布 ----- */
    .cases-grid {
      display: grid;
      grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
      gap: var(--grid-gutter);
    }
    .case-card img {
      width: 100%;
      aspect-ratio: 16 / 10;
      object-fit: cover;
      transition: transform var(--transition-smooth);
    }
    .case-card:hover img {
      transform: scale(1.03);
    }
    .case-content {
      padding: 24px;
      display: flex;
      flex-direction: column;
      gap: 12px;
    }
    .tags {
      display: flex;
      flex-wrap: wrap;
      gap: 8px;
    }
    .tag {
      background: #F0F0F5;
      color: var(--text-secondary);
      font-size: 12px;
      padding: 4px 10px;
      border-radius: 20px;
      font-weight: 500;
    }

    /* ----- 方案对比卡片 ----- */
    .compare-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: var(--grid-gutter);
    }
    .compare-card {
      background: var(--white);
      border-radius: var(--radius-card);
      padding: var(--card-padding);
      box-shadow: var(--shadow-card);
      display: flex;
      flex-direction: column;
      border: 1px solid transparent;
      transition: all var(--transition-fast);
    }
    .compare-card.featured {
      border-left: 4px solid var(--accent);
      background: rgba(233, 69, 96, 0.02);
    }
    .compare-name {
      font-size: 22px;
      font-weight: 700;
      margin-bottom: 8px;
    }
    .compare-price {
      font-size: 20px;
      font-weight: 600;
      color: var(--accent);
      margin-bottom: 24px;
    }
    .feature-list {
      list-style: none;
      display: flex;
      flex-direction: column;
      gap: 14px;
      margin-bottom: 32px;
      flex: 1;
    }
    .feature-list li {
      display: flex;
      align-items: center;
      gap: 10px;
      font-size: 15px;
      color: var(--text-secondary);
    }
    .check {
      color: var(--accent);
      font-weight: 700;
    }
    .cross {
      color: #A0A0B0;
    }

    /* ----- FAQ 手风琴 ----- */
    .faq-list {
      display: flex;
      flex-direction: column;
      border-top: 1px solid var(--border-light);
    }
    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }
    .faq-question {
      width: 100%;
      background: none;
      border: none;
      text-align: left;
      font-size: 18px;
      font-weight: 600;
      padding: 20px 0;
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      color: var(--text-primary);
    }
    .faq-icon {
      font-size: 22px;
      color: var(--accent);
      transition: transform var(--transition-fast);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s ease;
      background: var(--bg-light);
      border-radius: 8px;
      padding: 0 16px;
      margin-bottom: 8px;
      color: var(--text-secondary);
      line-height: 1.7;
    }
    .faq-item.open .faq-answer {
      max-height: 200px;
      padding: 16px;
    }
    .faq-item.open .faq-icon {
      transform: rotate(45deg);
    }

    /* ----- 联系 CTA ----- */
    .cta-wrapper {
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      gap: 24px;
    }
    .cta-form {
      display: flex;
      gap: 12px;
      flex-wrap: wrap;
      justify-content: center;
    }
    .cta-input {
      height: 48px;
      padding: 0 16px;
      border-radius: var(--radius-btn);
      border: 1px solid var(--border-light);
      background: var(--white);
      width: 320px;
      max-width: 90vw;
      font-size: 16px;
    }

    /* ----- 页脚 ----- */
    .site-footer {
      background: var(--bg-footer);
      color: var(--text-muted-on-dark);
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr;
      gap: 40px;
    }
    .footer-logo {
      font-size: 22px;
      font-weight: 700;
      color: var(--white);
    }
    .footer-desc {
      font-size: 14px;
      line-height: 1.6;
      margin-top: 12px;
      max-width: 280px;
    }
    .footer-links a {
      display: block;
      color: var(--text-muted-on-dark);
      margin-bottom: 10px;
      font-size: 15px;
    }
    .footer-links a:hover {
      color: var(--white);
    }
    .copyright {
      border-top: 1px solid rgba(255,255,255,0.08);
      margin-top: 40px;
      padding-top: 20px;
      text-align: center;
      font-size: 12px;
      color: rgba(204,204,213,0.8);
    }

    /* ----- 响应式断点 ----- */
    @media (max-width: 1024px) {
      :root {
        --section-gap: 80px;
        --card-padding: 24px;
      }
      h1 { font-size: 40px; line-height: 48px; }
      h2 { font-size: 30px; line-height: 38px; }
      .compare-grid { grid-template-columns: 1fr 1fr; }
    }
    @media (max-width: 768px) {
      :root {
        --section-gap: 60px;
        --grid-gutter: 24px;
      }
      .nav-links { display: none; }
      .menu-toggle { display: flex; }
      .mobile-menu.active { display: flex; }
      .hero-grid {
        grid-template-columns: 1fr;
        min-height: auto;
        gap: 40px;
      }
      .hero-left { order: 2; text-align: center; align-items: center; }
      .hero-visual { order: 1; }
      .hero-image { max-height: 320px; }
      h1 { font-size: 32px; line-height: 40px; }
      h2 { font-size: 26px; line-height: 34px; }
      .highlights-grid { grid-template-columns: repeat(2, 1fr); }
      .compare-grid { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr; gap: 32px; }
      .cta-input { width: 100%; }
      .btn { height: 44px; }
    }
    @media (max-width: 520px) {
      .highlights-grid { grid-template-columns: 1fr; }
      .cases-grid { grid-template-columns: 1fr; }
    }