/* roulang page: index */
/* ===== 设计变量与全局重置 ===== */
    :root {
      --primary: #0A2540;
      --primary-soft: #1A3148;
      --accent: #00A3FF;
      --accent-light: #E6F7FF;
      --bg-light: #F6F9FC;
      --white: #FFFFFF;
      --cta: #FF6B35;
      --cta-hover: #E55A2B;
      --text-dark: #1A1A2E;
      --text-muted: #5A6070;
      --border: #E2E8F0;
      --shadow-sm: 0 4px 20px rgba(10, 37, 64, 0.06);
      --shadow-md: 0 8px 30px rgba(10, 37, 64, 0.12);
      --radius-card: 16px;
      --radius-btn: 8px;
      --radius-input: 6px;
      --transition: all 0.25s ease;
      --font-heading: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
      --font-body: 'PingFang SC', 'Microsoft YaHei', 'Segoe UI', sans-serif;
    }
    * {
      box-sizing: border-box;
    }
    body {
      margin: 0;
      font-family: var(--font-body);
      color: var(--text-dark);
      background-color: var(--white);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: var(--transition);
    }
    button, input, textarea {
      font-family: inherit;
      font-size: inherit;
      outline: none;
      border: none;
    }
    /* 容器 */
    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 24px;
      width: 100%;
    }
    /* 区块间距 */
    section {
      padding: 80px 0;
    }
    @media (max-width: 768px) {
      section {
        padding: 60px 0;
      }
      .container {
        padding: 0 20px;
      }
    }
    /* 标题层级 */
    h1 {
      font-family: var(--font-heading);
      font-size: 36px;
      line-height: 1.3;
      font-weight: 700;
      letter-spacing: -0.5px;
      color: var(--primary);
    }
    h2 {
      font-family: var(--font-heading);
      font-size: 28px;
      line-height: 1.35;
      font-weight: 600;
      color: var(--primary);
      margin-bottom: 16px;
    }
    h3 {
      font-family: var(--font-heading);
      font-size: 20px;
      font-weight: 600;
      color: var(--text-dark);
    }
    .text-muted {
      color: var(--text-muted);
    }
    .section-subtitle {
      font-size: 1.1rem;
      color: var(--text-muted);
      margin-bottom: 40px;
      max-width: 700px;
    }
    /* 按钮样式 */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 0.85rem 2rem;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 1rem;
      transition: var(--transition);
      cursor: pointer;
      text-align: center;
      min-width: 120px;
      border: 2px solid transparent;
      background: transparent;
    }
    .btn-primary {
      background-color: var(--accent);
      color: white;
      border-color: var(--accent);
    }
    .btn-primary:hover {
      background-color: #0088cc;
      border-color: #0088cc;
    }
    .btn-cta {
      background-color: var(--cta);
      color: white;
      border-color: var(--cta);
      box-shadow: 0 4px 12px rgba(255, 107, 53, 0.3);
    }
    .btn-cta:hover {
      background-color: var(--cta-hover);
      border-color: var(--cta-hover);
      box-shadow: 0 6px 16px rgba(255, 107, 53, 0.4);
      transform: translateY(-1px);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--accent);
      color: var(--accent);
    }
    .btn-outline:hover {
      background-color: var(--accent);
      color: white;
    }
    /* 导航 */
    #header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: rgba(255,255,255,0.96);
      backdrop-filter: blur(8px);
      height: 70px;
      display: flex;
      align-items: center;
      z-index: 1000;
      border-bottom: 1px solid var(--border);
      transition: box-shadow 0.3s;
    }
    .header-shadow {
      box-shadow: 0 4px 20px rgba(0,0,0,0.04);
    }
    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }
    .logo {
      font-family: var(--font-heading);
      font-weight: 700;
      font-size: 1.6rem;
      color: var(--primary);
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .logo i {
      color: var(--accent);
      font-size: 1.9rem;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 2rem;
      list-style: none;
      margin: 0;
      padding: 0;
    }
    .nav-links a {
      font-weight: 500;
      color: var(--text-dark);
      position: relative;
      padding: 8px 0;
      font-size: 0.98rem;
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent);
      transition: width 0.2s;
    }
    .nav-links a:hover::after,
    .nav-links a.active::after {
      width: 100%;
    }
    .nav-links a.active {
      color: var(--primary);
      font-weight: 600;
    }
    .hamburger {
      display: none;
      font-size: 1.8rem;
      cursor: pointer;
      color: var(--primary);
    }
    @media (max-width: 768px) {
      .nav-links {
        display: none;
        position: absolute;
        top: 70px;
        left: 0;
        width: 100%;
        background: white;
        flex-direction: column;
        padding: 24px;
        gap: 1.5rem;
        box-shadow: var(--shadow-md);
        border-top: 1px solid var(--border);
      }
      .nav-links.active {
        display: flex;
      }
      .hamburger {
        display: block;
      }
    }
    /* Hero 双栏 */
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 40px;
      align-items: center;
      min-height: 80vh;
      padding-top: 90px;
    }
    .hero-text h1 {
      margin-bottom: 20px;
    }
    .hero-text p {
      font-size: 1.2rem;
      color: var(--text-muted);
      margin-bottom: 28px;
    }
    .hero-image img {
      border-radius: 20px;
      box-shadow: var(--shadow-md);
      width: 100%;
      object-fit: cover;
    }
    @media (max-width: 768px) {
      .hero-grid {
        grid-template-columns: 1fr;
        text-align: center;
        padding-top: 100px;
      }
      .hero-image {
        order: -1;
      }
      h1 {
        font-size: 2rem;
      }
    }
    /* 卡片通用 */
    .card {
      background: var(--white);
      border-radius: var(--radius-card);
      padding: 28px 24px;
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
      height: 100%;
    }
    .card:hover {
      box-shadow: var(--shadow-md);
      transform: translateY(-4px);
    }
    .icon-circle {
      width: 56px;
      height: 56px;
      background: var(--accent-light);
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--accent);
      font-size: 1.8rem;
      margin-bottom: 20px;
    }
    /* 亮点网格 */
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    @media (max-width: 768px) {
      .grid-3 {
        grid-template-columns: 1fr;
      }
    }
    /* 案例瀑布流 */
    .waterfall {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 20px;
    }
    .case-card {
      border-radius: var(--radius-card);
      overflow: hidden;
      background: white;
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
    }
    .case-card:hover {
      transform: translateY(-5px);
      box-shadow: var(--shadow-md);
    }
    .case-img {
      position: relative;
      overflow: hidden;
      height: 200px;
    }
    .case-img img {
      width: 100%;
      height: 100%;
      object-fit: cover;
    }
    .overlay {
      position: absolute;
      inset: 0;
      background: linear-gradient(0deg, rgba(10,37,64,0.5) 0%, transparent 60%);
      opacity: 0;
      transition: 0.3s;
      display: flex;
      align-items: flex-end;
      padding: 16px;
      color: white;
      font-weight: 600;
    }
    .case-card:hover .overlay {
      opacity: 1;
    }
    @media (max-width: 768px) {
      .waterfall {
        grid-template-columns: 1fr;
      }
    }
    /* 对比表 */
    .compare-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 24px;
    }
    .compare-card {
      background: white;
      border-radius: var(--radius-card);
      padding: 28px;
      box-shadow: var(--shadow-sm);
      border: 2px solid transparent;
    }
    .compare-card.recommend {
      border-color: var(--accent);
      position: relative;
    }
    .badge {
      background: var(--accent);
      color: white;
      padding: 4px 12px;
      border-radius: 20px;
      font-size: 0.8rem;
      font-weight: 600;
      display: inline-block;
    }
    @media (max-width: 640px) {
      .compare-grid {
        grid-template-columns: 1fr;
      }
    }
    /* FAQ 手风琴 */
    .faq-item {
      border-bottom: 1px solid var(--border);
      padding: 20px 0;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      font-weight: 600;
      font-size: 1.1rem;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      background: var(--bg-light);
      border-radius: 8px;
      margin-top: 8px;
      padding: 0 16px;
      color: var(--text-muted);
    }
    .faq-item.active .faq-answer {
      max-height: 120px;
      padding: 14px 16px;
    }
    /* 表单 */
    .form-row {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 16px;
      margin-bottom: 20px;
    }
    input, textarea {
      width: 100%;
      padding: 14px 16px;
      border: 1px solid var(--border);
      border-radius: var(--radius-input);
      background: white;
      transition: 0.2s;
    }
    input:focus, textarea:focus {
      border-color: var(--accent);
      box-shadow: 0 0 0 3px rgba(0,163,255,0.1);
    }
    @media (max-width: 640px) {
      .form-row {
        grid-template-columns: 1fr;
      }
    }
    /* 页脚 */
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 30px;
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }
    hr {
      border: 0.5px solid var(--border);
    }