/* roulang page: index */
:root {
      --primary: #D32F2F;
      --primary-deep: #B71C1C;
      --primary-light: #FFEBEE;
      --secondary: #1E1E1E;
      --accent: #F57C00;
      --bg: #FAFAFA;
      --card-bg: #FFFFFF;
      --text: #333333;
      --text-dark: #1E1E1E;
      --text-light: #FFFFFF;
      --text-muted: #777777;
      --border: #E0E0E0;
      --radius: 12px;
      --shadow-sm: 0 4px 20px rgba(0,0,0,0.04);
      --shadow-md: 0 8px 30px rgba(0,0,0,0.08);
      --font-stack: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
      --gap: 1.25rem;
      --section-padding: 5rem 0;
      --transition: all 0.25s ease;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    html {
      scroll-behavior: smooth;
      font-size: 16px;
    }
    body {
      font-family: var(--font-stack);
      background: var(--bg);
      color: var(--text);
      line-height: 1.75;
      -webkit-font-smoothing: antialiased;
      overflow-x: hidden;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
    }
    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 2rem;
    }
    /* 导航 */
    .navbar {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      transition: var(--transition);
      padding: 1rem 0;
      background: transparent;
    }
    .navbar.scrolled {
      background: rgba(255,255,255,0.96);
      backdrop-filter: blur(8px);
      box-shadow: 0 2px 12px rgba(0,0,0,0.04);
      padding: 0.6rem 0;
    }
    .navbar.scrolled .nav-logo {
      color: var(--secondary);
    }
    .navbar.scrolled .nav-link {
      color: var(--text-dark);
    }
    .navbar.scrolled .nav-link:hover,
    .navbar.scrolled .nav-link.active {
      color: var(--primary);
    }
    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
    }
    .nav-logo {
      font-size: 1.6rem;
      font-weight: 700;
      letter-spacing: 0.02em;
      display: flex;
      align-items: center;
      gap: 0.4rem;
      color: #fff;
      transition: color 0.3s;
    }
    .nav-logo span {
      color: var(--primary);
    }
    .nav-menu {
      display: flex;
      align-items: center;
      gap: 2rem;
    }
    .nav-link {
      font-weight: 500;
      font-size: 1rem;
      transition: var(--transition);
      position: relative;
      padding: 0.2rem 0;
      color: rgba(255,255,255,0.9);
    }
    .nav-link::after {
      content: '';
      position: absolute;
      left: 0;
      bottom: -2px;
      width: 0;
      height: 2px;
      background: var(--primary);
      transition: width 0.25s ease;
    }
    .nav-link:hover::after,
    .nav-link.active::after {
      width: 100%;
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      background: none;
      border: none;
      cursor: pointer;
      padding: 4px;
    }
    .hamburger span {
      width: 25px;
      height: 2px;
      background: #fff;
      transition: var(--transition);
      display: block;
    }
    .navbar.scrolled .hamburger span {
      background: var(--secondary);
    }
    /* 首屏 Hero */
    .hero {
      position: relative;
      min-height: 100vh;
      display: flex;
      align-items: center;
      justify-content: center;
      background: url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      background-attachment: fixed;
      color: #fff;
      text-align: center;
      overflow: hidden;
    }
    .hero-overlay {
      position: absolute;
      inset: 0;
      background: linear-gradient(180deg, rgba(0,0,0,0.3) 0%, rgba(30,30,30,0.75) 100%);
      z-index: 1;
    }
    .hero-content {
      position: relative;
      z-index: 2;
      max-width: 900px;
      padding: 0 2rem;
    }
    .hero h1 {
      font-size: clamp(2.4rem, 6vw, 4rem);
      font-weight: 800;
      letter-spacing: 0.02em;
      margin-bottom: 1.5rem;
      line-height: 1.2;
      color: #fff;
      text-shadow: 0 4px 20px rgba(0,0,0,0.3);
    }
    .hero h1 span {
      color: var(--primary);
    }
    .hero .subtitle {
      font-size: 1.25rem;
      margin-bottom: 2.2rem;
      color: rgba(255,255,255,0.85);
      font-weight: 400;
    }
    .btn-group {
      display: flex;
      gap: 1rem;
      justify-content: center;
      flex-wrap: wrap;
    }
    .btn {
      display: inline-block;
      font-weight: 600;
      padding: 0.8rem 2.2rem;
      border-radius: 30px;
      transition: var(--transition);
      font-size: 1rem;
      text-align: center;
      white-space: nowrap;
    }
    .btn-primary {
      background: var(--primary);
      color: #fff;
      box-shadow: 0 6px 18px rgba(211,47,47,0.3);
    }
    .btn-primary:hover {
      background: var(--primary-deep);
      transform: translateY(-2px);
      box-shadow: 0 10px 24px rgba(183,28,28,0.35);
    }
    .btn-outline {
      border: 2px solid rgba(255,255,255,0.9);
      color: #fff;
      background: transparent;
    }
    .btn-outline:hover {
      background: rgba(255,255,255,0.15);
      border-color: #fff;
    }
    /* 板块通用 */
    section {
      padding: var(--section-padding);
    }
    .section-title {
      font-size: 2.4rem;
      font-weight: 700;
      color: var(--text-dark);
      text-align: center;
      margin-bottom: 0.75rem;
    }
    .section-sub {
      text-align: center;
      color: var(--text-muted);
      margin-bottom: 3rem;
      font-size: 1.1rem;
    }
    .grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
      gap: var(--gap);
    }
    .card {
      background: var(--card-bg);
      border-radius: var(--radius);
      padding: 2rem;
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
      display: flex;
      flex-direction: column;
      align-items: flex-start;
    }
    .card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-md);
    }
    .card-icon {
      font-size: 2.3rem;
      color: var(--primary);
      margin-bottom: 1.2rem;
    }
    .card h3 {
      font-size: 1.4rem;
      font-weight: 600;
      margin-bottom: 0.7rem;
      color: var(--text-dark);
    }
    .card p {
      color: #555;
    }
    .services-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 1.5rem;
    }
    .services-grid .card:first-child {
      grid-row: span 2;
    }
    .advantages {
      background: var(--secondary);
      color: #fff;
    }
    .advantages .section-title {
      color: #fff;
    }
    .stats {
      display: flex;
      justify-content: space-around;
      flex-wrap: wrap;
      text-align: center;
      gap: 2rem;
    }
    .stat-item h3 {
      font-size: 2.8rem;
      font-weight: 700;
      color: var(--accent);
      letter-spacing: 0.02em;
    }
    .stat-item p {
      color: rgba(255,255,255,0.8);
    }
    .cases-grid {
      display: grid;
      grid-template-columns: 1fr 1fr 1fr;
      gap: 1.5rem;
    }
    .case-card {
      background: var(--card-bg);
      border-radius: var(--radius);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
    }
    .case-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-md);
    }
    .case-img {
      height: 200px;
      background-size: cover;
      background-position: center;
      transition: transform 0.4s ease;
    }
    .case-card:hover .case-img {
      transform: scale(1.04);
    }
    .case-body {
      padding: 1.5rem;
    }
    .case-body h3 {
      margin-bottom: 0.5rem;
    }
    .tag {
      display: inline-block;
      background: var(--primary-light);
      color: var(--primary);
      padding: 0.2rem 0.8rem;
      border-radius: 20px;
      font-size: 0.8rem;
      font-weight: 600;
    }
    .solutions {
      background: #fff;
    }
    .steps {
      display: flex;
      justify-content: space-between;
      gap: 1.5rem;
      flex-wrap: wrap;
    }
    .step {
      flex: 1;
      text-align: center;
      padding: 2rem;
    }
    .step-num {
      background: var(--primary);
      color: #fff;
      width: 50px;
      height: 50px;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 1.4rem;
      font-weight: 700;
      margin: 0 auto 1rem;
    }
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }
    .faq-item {
      background: var(--card-bg);
      border-radius: var(--radius);
      margin-bottom: 0.8rem;
      box-shadow: var(--shadow-sm);
    }
    .faq-question {
      padding: 1.2rem 1.5rem;
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease;
      padding: 0 1.5rem;
      color: #444;
    }
    .faq-item.active .faq-answer {
      max-height: 300px;
      padding-bottom: 1.2rem;
    }
    .cta-block {
      background: linear-gradient(135deg, var(--primary) 0%, #b71c1c 100%);
      text-align: center;
      color: #fff;
    }
    .cta-block h2 {
      font-size: 2.5rem;
      margin-bottom: 1rem;
    }
    .btn-white {
      background: #fff;
      color: var(--primary);
      margin-top: 1.5rem;
    }
    .footer {
      background: #111;
      color: #ccc;
      padding: 3rem 0 1.5rem;
    }
    .footer-grid {
      display: flex;
      justify-content: space-between;
      flex-wrap: wrap;
      gap: 2rem;
      margin-bottom: 2rem;
    }
    .footer a {
      color: #ccc;
    }
    .footer a:hover {
      color: #fff;
    }
    @media (max-width: 768px) {
      .nav-menu {
        position: fixed;
        top: 0;
        right: -100%;
        height: 100vh;
        width: 70%;
        background: #fff;
        flex-direction: column;
        padding: 5rem 2rem;
        box-shadow: -5px 0 20px rgba(0,0,0,0.1);
        transition: right 0.3s ease;
        gap: 2rem;
      }
      .nav-menu.active {
        right: 0;
      }
      .hamburger {
        display: flex;
        z-index: 1001;
      }
      .services-grid {
        grid-template-columns: 1fr;
      }
      .cases-grid {
        grid-template-columns: 1fr;
      }
      .stats {
        flex-direction: column;
      }
    }