/* roulang page: index */
:root {
      --primary: #1B2A3A;
      --accent: #C8A96E;
      --accent-hover: #B8954F;
      --bg-light: #F4F7FA;
      --text-dark: #1A1A1A;
      --text-mid: #5A5A5A;
      --text-light: #8A8A8A;
      --white: #FFFFFF;
      --border-light: #E8ECF1;
      --shadow-sm: 0 4px 12px rgba(0,0,0,0.04);
      --shadow-card: 0 4px 20px rgba(0,0,0,0.06);
      --shadow-hover: 0 8px 30px rgba(0,0,0,0.10);
      --radius-card: 8px;
      --radius-btn: 6px;
      --radius-tag: 20px;
      --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
      --nav-width: 240px;
      --mobile-nav-height: 56px;
      --font-sans: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Inter", "Segoe UI", sans-serif;
    }

    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

    html {
      scroll-behavior: smooth;
    }

    body {
      font-family: var(--font-sans);
      background-color: var(--white);
      color: var(--text-dark);
      line-height: 1.6;
      display: flex;
      min-height: 100vh;
      -webkit-font-smoothing: antialiased;
    }

    /* 左侧导航 (App Shell) */
    .app-nav {
      position: fixed;
      left: 0;
      top: 0;
      width: var(--nav-width);
      height: 100vh;
      background-color: var(--primary);
      display: flex;
      flex-direction: column;
      padding: 2rem 1.5rem;
      z-index: 100;
      box-shadow: 2px 0 15px rgba(0,0,0,0.08);
      transition: transform 0.3s ease;
    }

    .nav-logo {
      display: flex;
      align-items: center;
      gap: 0.75rem;
      margin-bottom: 3rem;
      padding-left: 0.5rem;
      text-decoration: none;
    }

    .logo-icon {
      width: 32px;
      height: 32px;
      background: var(--accent);
      border-radius: 6px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--primary);
      font-weight: 700;
      font-size: 18px;
    }

    .logo-text {
      font-size: 1.25rem;
      font-weight: 600;
      color: var(--white);
      letter-spacing: 0.5px;
    }

    .nav-links {
      list-style: none;
      display: flex;
      flex-direction: column;
      gap: 0.5rem;
      flex: 1;
    }

    .nav-links a {
      display: flex;
      align-items: center;
      padding: 0.75rem 1rem;
      color: rgba(255,255,255,0.7);
      text-decoration: none;
      font-size: 0.95rem;
      font-weight: 500;
      border-radius: 6px;
      position: relative;
      transition: color var(--transition), background-color var(--transition), padding-left var(--transition);
      letter-spacing: 0.3px;
    }

    .nav-links a::before {
      content: '';
      position: absolute;
      left: 0;
      top: 20%;
      height: 60%;
      width: 3px;
      background-color: var(--accent);
      border-radius: 0 4px 4px 0;
      transform: scaleY(0);
      transition: transform var(--transition);
    }

    .nav-links a:hover,
    .nav-links a.active {
      color: var(--white);
      background-color: rgba(255,255,255,0.05);
      padding-left: 1.4rem;
    }

    .nav-links a:hover::before,
    .nav-links a.active::before {
      transform: scaleY(1);
    }

    .mobile-menu-toggle {
      display: none;
      background: none;
      border: none;
      color: var(--white);
      font-size: 1.8rem;
      cursor: pointer;
      line-height: 1;
      padding: 0.25rem;
    }

    /* 主内容区 */
    .main-content {
      margin-left: var(--nav-width);
      flex: 1;
      width: calc(100% - var(--nav-width));
      background-color: var(--white);
    }

    /* 通用板块 */
    .section {
      padding: 100px 80px;
    }

    .container {
      max-width: 960px;
      margin: 0 auto;
      width: 100%;
    }

    h2 {
      font-size: 2.25rem;
      font-weight: 600;
      margin-bottom: 1.5rem;
      letter-spacing: -0.3px;
      color: var(--text-dark);
      position: relative;
      display: inline-block;
    }

    .title-decor {
      width: 48px;
      height: 4px;
      background-color: var(--accent);
      margin-bottom: 2.5rem;
      border-radius: 2px;
    }

    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 0.8rem 2rem;
      font-weight: 600;
      border-radius: var(--radius-btn);
      text-decoration: none;
      transition: all var(--transition);
      cursor: pointer;
      border: none;
      font-size: 1rem;
      letter-spacing: 0.4px;
      min-width: 140px;
    }

    .btn-primary {
      background-color: var(--accent);
      color: var(--white);
      box-shadow: 0 4px 10px rgba(200,169,110,0.25);
    }

    .btn-primary:hover {
      background-color: var(--accent-hover);
      transform: translateY(-2px);
      box-shadow: 0 8px 18px rgba(184,149,79,0.3);
    }

    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--white);
      color: var(--white);
    }

    .btn-outline:hover {
      background-color: rgba(255,255,255,0.08);
      border-color: rgba(255,255,255,0.9);
    }

    /* Hero */
    #hero {
      height: 100vh;
      display: flex;
      align-items: center;
      background: linear-gradient(135deg, rgba(27,42,58,0.85) 0%, rgba(27,42,58,0.4) 100%), url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      color: var(--white);
      padding: 0 80px;
      position: relative;
    }

    .hero-content {
      max-width: 700px;
    }

    .hero-content h1 {
      font-size: 3.5rem;
      font-weight: 700;
      line-height: 1.2;
      margin-bottom: 1.5rem;
      letter-spacing: 0.2px;
    }

    .hero-sub {
      font-size: 1.2rem;
      opacity: 0.85;
      margin-bottom: 2.5rem;
      font-weight: 400;
    }

    .hero-actions {
      display: flex;
      gap: 1.25rem;
      flex-wrap: wrap;
    }

    .scroll-indicator {
      position: absolute;
      bottom: 30px;
      left: 50%;
      transform: translateX(-50%);
      font-size: 2rem;
      opacity: 0.7;
      animation: float 2s infinite;
      color: var(--white);
    }

    @keyframes float {
      0%,100% { transform: translateX(-50%) translateY(0); }
      50% { transform: translateX(-50%) translateY(8px); }
    }

    /* 核心业务卡片 */
    .services-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }

    .service-card {
      position: relative;
      border-radius: var(--radius-card);
      overflow: hidden;
      height: 360px;
      background: #ddd;
      box-shadow: var(--shadow-card);
      transition: transform 0.4s ease, box-shadow 0.4s ease;
    }

    .service-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-hover);
    }

    .service-card img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      transition: transform 0.4s ease;
    }

    .service-card:hover img {
      transform: scale(1.05);
    }

    .service-caption {
      position: absolute;
      bottom: 0;
      left: 0;
      right: 0;
      padding: 2rem 1.5rem;
      background: linear-gradient(transparent, rgba(0,0,0,0.75));
      color: white;
    }

    .service-caption h3 {
      font-size: 1.4rem;
      font-weight: 600;
      margin-bottom: 0.3rem;
    }

    .service-caption p {
      font-size: 0.9rem;
      opacity: 0.85;
    }

    /* 数据区块 */
    #data {
      background-color: var(--bg-light);
      text-align: center;
    }

    .stats-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 2rem;
    }

    .stat-item {
      display: flex;
      flex-direction: column;
      align-items: center;
    }

    .stat-number {
      font-size: 3rem;
      font-weight: 700;
      color: var(--accent);
      line-height: 1.2;
    }

    .stat-label {
      font-size: 0.95rem;
      color: var(--text-mid);
      margin-top: 0.4rem;
    }

    /* 案例卡片 */
    .cases-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 28px;
    }

    .case-card {
      display: flex;
      background: white;
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-card);
      transition: var(--transition);
    }

    .case-card:hover {
      box-shadow: var(--shadow-hover);
    }

    .case-img {
      width: 50%;
      object-fit: cover;
    }

    .case-info {
      padding: 2rem;
      display: flex;
      flex-direction: column;
      justify-content: center;
    }

    .case-tag {
      background: #f0f0f0;
      color: var(--text-mid);
      padding: 0.2rem 1rem;
      border-radius: 20px;
      font-size: 0.8rem;
      display: inline-block;
      margin-bottom: 0.8rem;
      width: fit-content;
    }

    .case-info h3 {
      font-size: 1.5rem;
      font-weight: 600;
      margin-bottom: 0.5rem;
    }

    .case-link {
      color: var(--accent);
      text-decoration: none;
      font-weight: 600;
      margin-top: 1rem;
      display: inline-flex;
      align-items: center;
      gap: 4px;
    }

    .case-link span {
      transition: transform 0.2s;
    }

    .case-link:hover span {
      transform: translateX(6px);
    }

    /* FAQ */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }

    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 1.2rem 0;
    }

    .faq-question {
      display: flex;
      align-items: center;
      justify-content: space-between;
      cursor: pointer;
      font-weight: 600;
      font-size: 1.1rem;
    }

    .faq-q {
      color: var(--accent);
      font-weight: 700;
      margin-right: 1rem;
      font-size: 1.3rem;
    }

    .faq-arrow {
      transition: transform 0.3s;
      font-size: 1.2rem;
      color: var(--text-light);
    }

    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease, padding 0.4s;
      color: var(--text-mid);
      padding-left: 2.2rem;
    }

    .faq-item.open .faq-answer {
      max-height: 200px;
      padding-top: 0.8rem;
    }

    .faq-item.open .faq-arrow {
      transform: rotate(180deg);
    }

    /* CTA 区块 */
    #contact {
      background-color: var(--primary);
      color: white;
      text-align: center;
    }

    .glass-cards {
      display: flex;
      gap: 24px;
      justify-content: center;
      margin-top: 3rem;
      flex-wrap: wrap;
    }

    .glass-card {
      background: rgba(255,255,255,0.06);
      backdrop-filter: blur(10px);
      border: 1px solid rgba(255,255,255,0.12);
      border-radius: 12px;
      padding: 1.8rem 2rem;
      min-width: 200px;
      color: white;
    }

    /* Footer */
    .footer {
      background: #0F1A26;
      color: rgba(255,255,255,0.7);
      padding: 3rem 80px 1.5rem;
    }

    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 2rem;
      max-width: 960px;
      margin: 0 auto;
    }

    .footer a {
      color: rgba(255,255,255,0.6);
      text-decoration: none;
      font-size: 0.9rem;
      transition: color 0.2s;
    }

    .footer a:hover {
      color: var(--accent);
    }

    .copyright {
      border-top: 1px solid rgba(255,255,255,0.1);
      margin-top: 2.5rem;
      padding-top: 1.5rem;
      text-align: center;
      font-size: 0.85rem;
    }

    /* 移动端响应式 */
    @media (max-width: 1024px) {
      .app-nav {
        transform: translateX(-100%);
        width: 260px;
        top: 0;
      }
      .app-nav.mobile-open {
        transform: translateX(0);
      }
      .mobile-menu-toggle {
        display: block;
        position: fixed;
        top: 12px;
        right: 16px;
        z-index: 110;
        background: var(--primary);
        border-radius: 8px;
        padding: 8px 12px;
      }
      .main-content {
        margin-left: 0;
        width: 100%;
      }
      .section {
        padding: 80px 40px;
      }
      #hero {
        padding: 0 40px;
      }
    }

    @media (max-width: 768px) {
      .services-grid, .stats-grid, .cases-grid {
        grid-template-columns: 1fr;
      }
      .case-card {
        flex-direction: column;
      }
      .case-img {
        width: 100%;
        height: 200px;
      }
      .hero-content h1 {
        font-size: 2.2rem;
      }
      .section {
        padding: 70px 20px;
      }
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
      .glass-cards {
        flex-direction: column;
        align-items: center;
      }
    }