/* roulang page: index */
:root {
      --primary: #0F6FDE;
      --primary-dark: #0B5EC2;
      --accent: #00A86B;
      --bg-light: #F4F8FC;
      --bg-white: #FFFFFF;
      --text-heading: #0F172A;
      --text-body: #475569;
      --text-muted: #94A3B8;
      --border-light: #E2E8F0;
      --footer-bg: #1E293B;
      --card-shadow: 0 8px 24px rgba(15, 111, 222, 0.08);
      --card-shadow-hover: 0 16px 32px rgba(15, 111, 222, 0.12);
      --radius-md: 12px;
      --radius-sm: 8px;
      --font-sans: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
      --transition: 0.25s ease-out;
    }
    * {
      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;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
      border-radius: var(--radius-md);
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color var(--transition);
    }
    .container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 24px;
    }
    /* 导航 */
    .site-header {
      position: sticky;
      top: 0;
      z-index: 50;
      background: rgba(255, 255, 255, 0.92);
      backdrop-filter: blur(12px);
      border-bottom: 1px solid rgba(226, 232, 240, 0.6);
      box-shadow: 0 4px 12px rgba(0,0,0,0.02);
    }
    .nav-bar {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 72px;
      gap: 24px;
    }
    .logo {
      display: flex;
      align-items: center;
      gap: 10px;
      font-size: 1.5rem;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: 0.5px;
    }
    .logo i {
      font-size: 2rem;
      color: var(--primary);
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 2rem;
    }
    .nav-links a {
      font-weight: 500;
      color: var(--text-heading);
      position: relative;
      padding: 4px 0;
      white-space: nowrap;
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      left: 0;
      bottom: -4px;
      width: 0;
      height: 2px;
      background: var(--primary);
      transition: width var(--transition);
    }
    .nav-links a:hover {
      color: var(--primary);
    }
    .nav-links a:hover::after {
      width: 100%;
    }
    .btn-primary {
      background: var(--primary);
      color: white;
      padding: 12px 28px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      font-size: 1rem;
      border: none;
      cursor: pointer;
      transition: background var(--transition), transform var(--transition);
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      white-space: nowrap;
    }
    .btn-primary:hover {
      background: var(--primary-dark);
      transform: translateY(-1px);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--primary);
      color: var(--primary);
      padding: 12px 28px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      cursor: pointer;
      transition: all var(--transition);
    }
    .btn-outline:hover {
      background: rgba(15, 111, 222, 0.06);
    }
    .hamburger {
      display: none;
      font-size: 1.8rem;
      cursor: pointer;
      color: var(--text-heading);
    }
    /* 移动端导航 */
    .mobile-menu {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100vh;
      background: rgba(255,255,255,0.98);
      backdrop-filter: blur(16px);
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 2.5rem;
      z-index: 100;
    }
    .mobile-menu a {
      font-size: 1.8rem;
      font-weight: 600;
      color: var(--text-heading);
    }
    .close-menu {
      position: absolute;
      top: 24px;
      right: 24px;
      font-size: 2.2rem;
      cursor: pointer;
    }
    /* Hero */
    .hero {
      background: linear-gradient(135deg, #F4F8FC 0%, #FFFFFF 100%);
      padding: 4rem 0 5rem;
    }
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 3rem;
    }
    .hero-left {
      flex: 0 0 55%;
    }
    .hero-right {
      flex: 0 0 45%;
      position: relative;
    }
    .hero h1 {
      font-size: clamp(2.4rem, 5vw, 3.8rem);
      font-weight: 700;
      color: var(--text-heading);
      line-height: 1.2;
      letter-spacing: -0.5px;
    }
    .hero-sub {
      font-size: 1.2rem;
      color: var(--text-body);
      margin: 1.5rem 0 2rem;
      max-width: 90%;
    }
    .hero-buttons {
      display: flex;
      gap: 1rem;
      flex-wrap: wrap;
    }
    .hero-image {
      background: #d9e6f2;
      border-radius: 20px;
      overflow: hidden;
      box-shadow: 0 20px 40px rgba(0,0,0,0.08);
      animation: float 4s ease-in-out infinite;
    }
    @keyframes float {
      0% { transform: translateY(0); }
      50% { transform: translateY(-6px); }
      100% { transform: translateY(0); }
    }
    /* 通用板块 */
    .section {
      padding: 4.5rem 0;
    }
    .section-title {
      text-align: center;
      font-size: 2.2rem;
      font-weight: 700;
      color: var(--text-heading);
      margin-bottom: 0.5rem;
    }
    .title-decor {
      width: 48px;
      height: 4px;
      background: var(--primary);
      margin: 0.5rem auto 2.5rem;
      border-radius: 4px;
    }
    /* 卡片网格 */
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 2rem;
    }
    .advantage-card {
      background: var(--bg-white);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-md);
      padding: 2rem 1.5rem;
      box-shadow: 0 4px 12px rgba(0,0,0,0.03);
      transition: all var(--transition);
      text-align: center;
    }
    .advantage-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--card-shadow);
    }
    .advantage-card i {
      font-size: 2.4rem;
      color: var(--primary);
      margin-bottom: 1rem;
    }
    .advantage-card h3 {
      font-size: 1.4rem;
      color: var(--text-heading);
      margin-bottom: 0.5rem;
    }
    /* 方案卡片 */
    .plan-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 2rem;
    }
    .plan-card {
      background: white;
      border: 1px solid var(--border-light);
      border-radius: var(--radius-md);
      padding: 2rem;
      display: flex;
      flex-direction: column;
      box-shadow: 0 4px 12px rgba(0,0,0,0.02);
      transition: all var(--transition);
    }
    .plan-card.featured {
      border: 2px solid var(--primary);
      position: relative;
    }
    .badge-hot {
      position: absolute;
      top: 16px;
      right: 16px;
      background: var(--accent);
      color: white;
      padding: 4px 14px;
      border-radius: 20px;
      font-size: 0.8rem;
      font-weight: 600;
    }
    .plan-card h3 {
      font-size: 1.6rem;
      margin-bottom: 0.8rem;
    }
    .plan-price {
      font-size: 2rem;
      font-weight: 700;
      color: var(--primary);
    }
    .plan-list {
      list-style: none;
      margin: 1.5rem 0;
      flex:1;
    }
    .plan-list li {
      padding: 0.5rem 0;
      border-bottom: 1px solid #f1f5f9;
    }
    /* 案例瀑布流 */
    .case-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 1.5rem;
    }
    .case-card {
      border-radius: var(--radius-md);
      overflow: hidden;
      background: white;
      box-shadow: 0 4px 12px rgba(0,0,0,0.04);
      transition: all var(--transition);
    }
    .case-card:hover {
      transform: scale(1.02);
    }
    .case-img {
      height: 180px;
      background: #cbd5e1;
    }
    .case-info {
      padding: 1rem;
    }
    /* 数据条 */
    .stats-band {
      background: #EBF2FA;
      display: flex;
      justify-content: center;
      flex-wrap: wrap;
      gap: 3rem;
      padding: 2.5rem 1rem;
      text-align: center;
    }
    .stat-item h3 {
      font-size: 2.8rem;
      color: var(--primary);
    }
    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 1.2rem 0;
      cursor: pointer;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      font-weight: 600;
      color: var(--text-heading);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      color: var(--text-body);
    }
    /* 联系表单 */
    .contact-block {
      background: linear-gradient(120deg, #0F6FDE, #1e4b8a);
      color: white;
      border-radius: 24px;
      padding: 3rem;
      display: flex;
      gap: 2rem;
    }
    .form-card {
      background: white;
      color: #0F172A;
      border-radius: 16px;
      padding: 2rem;
      flex: 1;
    }
    .form-card input, .form-card textarea {
      width: 100%;
      padding: 14px;
      margin: 10px 0;
      border: 1px solid #CBD5E1;
      border-radius: 8px;
      font-size: 1rem;
    }
    .form-card input:focus, .form-card textarea:focus {
      border-color: var(--primary);
      outline: none;
      box-shadow: 0 0 0 3px rgba(15,111,222,0.2);
    }
    /* 页脚 */
    .footer {
      background: var(--footer-bg);
      color: #cbd5e1;
      padding: 3rem 0 1.5rem;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 2rem;
    }
    .footer a {
      color: #cbd5e1;
    }
    .footer a:hover {
      color: white;
      text-decoration: underline;
    }
    @media (max-width: 1024px) {
      .hero-grid { flex-direction: column; }
      .grid-3, .plan-grid { grid-template-columns: repeat(2, 1fr); }
      .case-grid { grid-template-columns: repeat(2, 1fr); }
      .contact-block { flex-direction: column; }
      .footer-grid { grid-template-columns: repeat(2, 1fr); }
      .nav-links { display: none; }
      .hamburger { display: block; }
    }
    @media (max-width: 640px) {
      .grid-3, .plan-grid, .case-grid { grid-template-columns: 1fr; }
      .hero h1 { font-size: 2.2rem; }
    }