/* roulang page: index */
/* 设计变量 */
    :root {
      --primary: #E8614D;
      --primary-dark: #D14A37;
      --secondary: #1A2F3B;
      --accent: #5DADE2;
      --accent-light: rgba(93, 173, 226, 0.1);
      --bg-light: #F7F9FA;
      --white: #FFFFFF;
      --text-dark: #1A2F3B;
      --text-muted: #6B7B83;
      --text-footer: #B0BEC5;
      --border-light: #E0E7EA;
      --shadow-xs: 0 2px 12px rgba(26,47,59,0.06);
      --shadow-md: 0 8px 24px rgba(26,47,59,0.10);
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-input: 6px;
      --max-width: 1200px;
      --nav-height: 72px;
    }
    
    /* 基础重置 */
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    
    html {
      scroll-behavior: smooth;
      scroll-padding-top: var(--nav-height);
    }
    
    body {
      font-family: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", sans-serif;
      font-size: 16px;
      font-weight: 400;
      line-height: 1.75;
      color: var(--text-dark);
      background-color: var(--bg-light);
      -webkit-font-smoothing: antialiased;
    }
    
    /* 容器 */
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }
    @media (max-width: 767px) {
      .container {
        padding: 0 16px;
      }
    }
    
    /* 图片通用 */
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    
    a {
      text-decoration: none;
      color: inherit;
    }
    
    button {
      font-family: inherit;
      cursor: pointer;
      border: none;
      background: transparent;
    }
    
    /* 导航 */
    .nav {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      background: var(--white);
      z-index: 1000;
      display: flex;
      align-items: center;
      border-bottom: 1px solid transparent;
      transition: box-shadow 0.25s ease, border-color 0.25s ease;
    }
    .nav.scrolled {
      box-shadow: 0 1px 8px rgba(0,0,0,0.06);
      border-bottom-color: var(--border-light);
    }
    .nav .container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
    }
    .logo {
      display: flex;
      flex-direction: column;
      align-items: flex-start;
      line-height: 1.2;
    }
    .logo-main {
      font-size: 24px;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: 0.5px;
    }
    .logo-domain {
      font-size: 10px;
      color: var(--text-muted);
      margin-top: 2px;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
      list-style: none;
    }
    .nav-links a {
      font-size: 15px;
      font-weight: 500;
      color: var(--text-dark);
      transition: color 0.2s;
      white-space: nowrap;
    }
    .nav-links a:hover {
      color: var(--primary);
    }
    .nav-cta {
      background: var(--primary);
      color: var(--white);
      padding: 10px 24px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 14px;
      transition: background 0.2s;
    }
    .nav-cta:hover {
      background: var(--primary-dark);
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      z-index: 1001;
    }
    .hamburger span {
      width: 24px;
      height: 2px;
      background: var(--secondary);
      border-radius: 2px;
      transition: all 0.3s ease;
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100vh;
      background: var(--white);
      z-index: 999;
      flex-direction: column;
      justify-content: center;
      align-items: center;
      gap: 32px;
      font-size: 20px;
      font-weight: 500;
      transform: translateY(-100%);
      transition: transform 0.3s ease;
    }
    .mobile-menu.active {
      transform: translateY(0);
    }
    @media (max-width: 767px) {
      .nav-links {
        display: none;
      }
      .hamburger {
        display: flex;
      }
      .mobile-menu {
        display: flex;
      }
    }
    
    /* 区块间距 */
    section {
      padding: 100px 0;
    }
    @media (max-width: 767px) {
      section {
        padding: 60px 0;
      }
    }
    
    /* 标题系统 */
    h1 {
      font-size: 52px;
      font-weight: 700;
      line-height: 1.2;
      letter-spacing: -0.5px;
      color: var(--secondary);
    }
    h2 {
      font-size: 34px;
      font-weight: 600;
      line-height: 1.3;
      text-align: center;
      margin-bottom: 16px;
      color: var(--secondary);
    }
    h3 {
      font-size: 21px;
      font-weight: 600;
      line-height: 1.4;
    }
    @media (max-width: 767px) {
      h1 {
        font-size: 38px;
      }
      h2 {
        font-size: 28px;
      }
    }
    
    /* 按钮系统 */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 16px;
      transition: all 0.2s ease;
      min-width: 130px;
      text-align: center;
    }
    .btn-primary {
      background: var(--primary);
      color: var(--white);
    }
    .btn-primary:hover {
      background: var(--primary-dark);
      transform: translateY(-1px);
    }
    .btn-outline {
      border: 2px solid var(--accent);
      color: var(--accent);
      background: transparent;
    }
    .btn-outline:hover {
      background: var(--accent);
      color: var(--white);
    }
    .btn-lg {
      padding: 18px 42px;
      font-size: 18px;
      border-radius: 10px;
    }
    
    /* 首屏 Hero */
    .hero {
      padding-top: calc(var(--nav-height) + 60px);
      padding-bottom: 100px;
      background-color: var(--bg-light);
      background-image: radial-gradient(circle at 20% 30%, rgba(93,173,226,0.08) 0%, transparent 40%);
    }
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 60px;
      align-items: center;
    }
    .hero-left {
      display: flex;
      flex-direction: column;
      gap: 24px;
    }
    .hero-subtitle {
      font-size: 18px;
      color: var(--text-muted);
      line-height: 1.6;
      max-width: 480px;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
      margin-top: 8px;
    }
    .hero-image img {
      border-radius: 20px;
      box-shadow: var(--shadow-md);
      width: 100%;
      aspect-ratio: 4/3;
      object-fit: cover;
    }
    @media (max-width: 1023px) {
      .hero-grid {
        grid-template-columns: 1fr;
        gap: 40px;
      }
      .hero-left {
        order: 1;
        text-align: center;
        align-items: center;
      }
      .hero-subtitle {
        max-width: 100%;
      }
      .hero-image {
        order: 0;
      }
    }
    
    /* 核心优势 */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
      margin-top: 48px;
    }
    .feature-card {
      background: var(--white);
      padding: 32px 24px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-xs);
      text-align: center;
      transition: transform 0.25s ease, box-shadow 0.25s ease;
    }
    .feature-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-md);
    }
    .feature-icon {
      font-size: 36px;
      color: var(--primary);
      margin-bottom: 16px;
    }
    .feature-card h3 {
      margin-bottom: 8px;
    }
    .feature-card p {
      font-size: 14px;
      color: var(--text-muted);
    }
    @media (max-width: 1023px) {
      .features-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }
    @media (max-width: 767px) {
      .features-grid {
        grid-template-columns: 1fr;
      }
    }
    
    /* 服务卡片 */
    .services-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
      margin-top: 48px;
    }
    .service-card {
      background: var(--white);
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-xs);
      transition: transform 0.25s ease, box-shadow 0.25s ease;
    }
    .service-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-md);
    }
    .service-card img {
      width: 100%;
      aspect-ratio: 16/9;
      object-fit: cover;
    }
    .service-card-body {
      padding: 24px;
    }
    .service-card-body h3 {
      margin-bottom: 4px;
    }
    .service-card-body p {
      font-size: 14px;
      color: var(--text-muted);
    }
    @media (max-width: 1023px) {
      .services-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }
    @media (max-width: 767px) {
      .services-grid {
        grid-template-columns: 1fr;
      }
    }
    
    /* 数据区 */
    .stats-section {
      background: var(--secondary);
      color: var(--white);
      text-align: center;
    }
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 32px;
      margin-top: 32px;
    }
    .stat-number {
      font-size: 48px;
      font-weight: 700;
      margin-bottom: 8px;
    }
    .stat-label {
      font-size: 14px;
      color: var(--accent);
      font-weight: 500;
    }
    @media (max-width: 767px) {
      .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 24px;
      }
    }
    
    /* 流程区 */
    .process-steps {
      display: flex;
      justify-content: center;
      align-items: flex-start;
      gap: 24px;
      margin-top: 48px;
      flex-wrap: wrap;
      position: relative;
    }
    .step {
      flex: 1;
      min-width: 150px;
      text-align: center;
      position: relative;
    }
    .step-circle {
      width: 48px;
      height: 48px;
      border-radius: 50%;
      background: var(--primary);
      color: var(--white);
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 700;
      font-size: 20px;
      margin: 0 auto 16px;
      position: relative;
      z-index: 2;
    }
    .step::after {
      content: '';
      position: absolute;
      top: 24px;
      left: calc(50% + 24px);
      width: calc(100% - 48px);
      height: 2px;
      background: #D0D8DC;
      z-index: 1;
    }
    .step:last-child::after {
      display: none;
    }
    .step h4 {
      font-size: 18px;
      font-weight: 600;
      margin-bottom: 4px;
    }
    .step p {
      font-size: 14px;
      color: var(--text-muted);
    }
    @media (max-width: 767px) {
      .process-steps {
        flex-direction: column;
        align-items: center;
        gap: 32px;
      }
      .step::after {
        left: 50%;
        top: auto;
        bottom: -32px;
        width: 2px;
        height: 32px;
        transform: translateX(-50%);
      }
    }
    
    /* 案例卡片 */
    .cases-grid {
      display: flex;
      flex-direction: column;
      gap: 20px;
      margin-top: 48px;
    }
    .case-card {
      display: flex;
      background: var(--white);
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-xs);
      overflow: hidden;
      transition: all 0.25s ease;
      border: 2px solid transparent;
    }
    .case-card:hover {
      border-color: var(--primary);
      box-shadow: var(--shadow-md);
    }
    .case-img {
      width: 180px;
      min-height: 140px;
      object-fit: cover;
      flex-shrink: 0;
    }
    .case-content {
      padding: 24px;
      display: flex;
      flex-direction: column;
      justify-content: center;
      gap: 8px;
    }
    .case-tag {
      display: inline-block;
      background: var(--accent-light);
      color: var(--accent);
      font-size: 13px;
      padding: 4px 12px;
      border-radius: 20px;
      font-weight: 500;
    }
    @media (max-width: 767px) {
      .case-card {
        flex-direction: column;
      }
      .case-img {
        width: 100%;
        height: 160px;
      }
    }
    
    /* FAQ */
    .faq-list {
      max-width: 800px;
      margin: 48px auto 0;
    }
    .faq-item {
      background: var(--white);
      border-radius: var(--radius-card);
      margin-bottom: 12px;
      box-shadow: var(--shadow-xs);
      overflow: hidden;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 20px 24px;
      font-weight: 600;
      font-size: 18px;
      cursor: pointer;
      background: var(--white);
      border: none;
      width: 100%;
      text-align: left;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s ease;
      background: var(--bg-light);
      padding: 0 24px;
      font-size: 15px;
      color: var(--text-dark);
      line-height: 1.75;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding: 16px 24px;
    }
    
    /* CTA */
    .cta-section {
      background: var(--secondary);
      color: var(--white);
      text-align: center;
      position: relative;
      overflow: hidden;
    }
    .cta-section::before {
      content: '';
      position: absolute;
      width: 300px;
      height: 300px;
      background: var(--primary);
      opacity: 0.08;
      border-radius: 50%;
      filter: blur(100px);
      top: -50px;
      right: -50px;
    }
    .cta-title {
      font-size: 36px;
      font-weight: 700;
      margin-bottom: 12px;
    }
    .cta-sub {
      color: #B0BEC5;
      margin-bottom: 32px;
    }
    
    /* 页脚 */
    .footer {
      background: var(--secondary);
      color: var(--text-footer);
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
      margin-bottom: 40px;
    }
    .footer-logo {
      font-size: 28px;
      font-weight: 700;
      color: var(--primary);
    }
    .footer-desc {
      font-size: 14px;
      margin-top: 8px;
    }
    .footer h4 {
      color: var(--white);
      margin-bottom: 16px;
      font-weight: 600;
    }
    .footer ul {
      list-style: none;
    }
    .footer li {
      margin-bottom: 8px;
      font-size: 14px;
    }
    .footer-bottom {
      border-top: 1px solid rgba(255,255,255,0.1);
      padding-top: 20px;
      text-align: center;
      font-size: 13px;
    }
    @media (max-width: 767px) {
      .footer-grid {
        grid-template-columns: 1fr;
        gap: 32px;
      }
    }
    
    /* 响应式工具 */
    @media (max-width: 767px) {
      .btn {
        width: 100%;
      }
    }