/* roulang page: index */
/* 核心设计变量 */
    :root {
      --primary-red: #E9403A;
      --deep-bg: #1A1C23;
      --accent-cyan: #00E5FF;
      --light-bg: #F4F4F6;
      --gray-text: #B0B3C1;
      --white-solid: #FFFFFF;
      --card-dark: #2A2D36;
      --radius-xl: 12px;
      --radius-md: 8px;
      --shadow-dark: 0 8px 30px rgba(0,0,0,0.4);
      --shadow-light: 0 4px 16px rgba(0,0,0,0.08);
      --transition-smooth: all 0.3s cubic-bezier(0.2, 0.9, 0.4, 1);
      --font-heading: 'PingFang SC', 'Noto Sans SC', 'Helvetica Neue', sans-serif;
      --font-body: 'Inter', 'PingFang SC', 'Noto Sans SC', sans-serif;
      --container-max: 1200px;
    }

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

    html {
      scroll-behavior: smooth;
      font-size: 16px;
      background-color: var(--deep-bg);
    }

    body {
      font-family: var(--font-body);
      background: var(--deep-bg);
      color: #f0f0f5;
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
      overflow-x: hidden;
    }

    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
    }

    /* 排版系统 */
    h1, h2, h3, .heading-xl {
      font-family: var(--font-heading);
      font-weight: 700;
      letter-spacing: -0.02em;
    }

    h1 {
      font-size: 3.25rem;
      line-height: 1.2;
    }

    h2 {
      font-size: 2.5rem;
      line-height: 1.25;
    }

    h3 {
      font-size: 1.5rem;
      font-weight: 600;
    }

    .section-heading {
      text-align: center;
      margin-bottom: 16px;
      color: var(--white-solid);
    }

    .section-sub {
      text-align: center;
      color: var(--gray-text);
      font-size: 1.15rem;
      margin-bottom: 56px;
      max-width: 640px;
      margin-left: auto;
      margin-right: auto;
    }

    /* 按钮系统 */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 14px 34px;
      border-radius: 60px;
      font-weight: 600;
      font-size: 1rem;
      transition: var(--transition-smooth);
      text-decoration: none;
      cursor: pointer;
      border: 2px solid transparent;
      gap: 8px;
    }

    .btn-primary {
      background: var(--primary-red);
      color: var(--white-solid);
      box-shadow: 0 6px 20px rgba(233,64,58,0.4);
    }
    .btn-primary:hover {
      background: #ff5249;
      box-shadow: 0 10px 28px rgba(233,64,58,0.7);
      transform: translateY(-2px);
      border-color: rgba(255,255,255,0.25);
    }

    .btn-ghost {
      border: 2px solid var(--accent-cyan);
      color: var(--accent-cyan);
      background: transparent;
      backdrop-filter: blur(4px);
    }
    .btn-ghost:hover {
      background: rgba(0,229,255,0.08);
      border-color: #4df0ff;
      color: #e6fcff;
    }

    .btn-white {
      background: white;
      color: #1a1c23;
      font-weight: 700;
      box-shadow: 0 8px 18px rgba(0,0,0,0.25);
    }
    .btn-white:hover {
      background: #f0f2f5;
      transform: scale(1.03);
    }

    /* 导航栏 */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      background: rgba(26,28,35,0.8);
      backdrop-filter: blur(20px);
      border-bottom: 1px solid rgba(0,229,255,0.2);
      transition: background 0.3s;
    }

    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 76px;
    }

    .logo {
      display: flex;
      align-items: center;
      gap: 6px;
      font-size: 1.8rem;
      font-weight: 800;
      color: white;
      text-decoration: none;
      letter-spacing: 2px;
      font-family: var(--font-heading);
    }
    .logo span {
      color: var(--primary-red);
    }
    .logo-icon {
      font-size: 2rem;
      margin-right: 6px;
      filter: drop-shadow(0 0 6px #E9403A);
    }

    .nav-links {
      display: flex;
      align-items: center;
      gap: 36px;
    }
    .nav-links a {
      color: var(--gray-text);
      text-decoration: none;
      font-weight: 500;
      position: relative;
      transition: color 0.2s;
      font-size: 0.95rem;
    }
    .nav-links a:hover,
    .nav-links a.active {
      color: white;
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: -6px;
      left: 0;
      width: 0%;
      height: 2px;
      background: var(--accent-cyan);
      transition: width 0.3s;
    }
    .nav-links a:hover::after {
      width: 100%;
    }

    .menu-toggle {
      display: none;
      background: none;
      border: none;
      color: white;
      font-size: 2rem;
      cursor: pointer;
    }

    @media (max-width: 768px) {
      .nav-links {
        position: fixed;
        top: 76px;
        left: 0;
        width: 100%;
        background: rgba(13,14,18,0.98);
        backdrop-filter: blur(30px);
        flex-direction: column;
        padding: 32px;
        gap: 24px;
        display: none;
        border-bottom: 1px solid var(--accent-cyan);
      }
      .nav-links.active {
        display: flex;
      }
      .menu-toggle {
        display: block;
      }
    }

    /* 区块共用 */
    section {
      padding: 120px 0;
      position: relative;
    }

    .bg-dark {
      background: var(--deep-bg);
    }
    .bg-light {
      background: var(--light-bg);
      color: #1a1c23;
    }
    .bg-light h2, .bg-light .section-heading {
      color: #0f0f12;
    }
    .bg-light .section-sub {
      color: #5a5c6e;
    }

    /* Hero */
    .hero {
      height: 100vh;
      min-height: 700px;
      display: flex;
      align-items: center;
      background: radial-gradient(circle at 20% 30%, #2a2035, #0d0e15 80%);
      position: relative;
      overflow: hidden;
      padding-top: 70px;
    }
    .hero::before {
      content: "";
      position: absolute;
      inset: 0;
      background-image: url('/assets/images/backpic/back-1.webp');
      background-size: cover;
      background-position: center;
      opacity: 0.25;
      mix-blend-mode: screen;
    }
    .hero-content {
      position: relative;
      z-index: 2;
      max-width: 820px;
    }
    .hero h1 {
      font-size: 4rem;
      font-weight: 800;
      line-height: 1.15;
      margin-bottom: 24px;
    }
    .hero .highlight {
      color: var(--accent-cyan);
    }
    .hero p {
      font-size: 1.3rem;
      color: var(--gray-text);
      margin-bottom: 40px;
    }
    .hero-actions {
      display: flex;
      gap: 20px;
      flex-wrap: wrap;
    }

    /* 服务卡片 */
    .grid-services {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 30px;
      margin-top: 30px;
    }
    .service-card {
      background: var(--card-dark);
      border-radius: var(--radius-xl);
      padding: 36px 28px;
      transition: var(--transition-smooth);
      border: 1px solid transparent;
    }
    .service-card:hover {
      transform: translateY(-8px);
      border-color: var(--accent-cyan);
      box-shadow: 0 18px 35px rgba(0,0,0,0.6);
    }
    .icon-glow {
      font-size: 2.8rem;
      margin-bottom: 22px;
      color: var(--accent-cyan);
    }
    .service-card h3 {
      margin-bottom: 14px;
    }

    /* 数据区 */
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      text-align: center;
      gap: 40px;
    }
    .stat-number {
      font-size: 3.8rem;
      font-weight: 800;
      color: var(--accent-cyan);
    }

    /* 案例 */
    .cases-row {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 32px;
    }
    .case-card {
      background: #181b22;
      border-radius: var(--radius-xl);
      overflow: hidden;
      display: flex;
    }
    .case-img {
      width: 45%;
      background-size: cover;
      background-position: center;
    }
    .case-info {
      padding: 32px;
    }

    /* FAQ */
    .faq-item {
      border-left: 4px solid var(--primary-red);
      padding: 18px 24px;
      margin-bottom: 20px;
      background: white;
      border-radius: 0 12px 12px 0;
      cursor: pointer;
    }
    .faq-item.active {
      border-left-color: var(--accent-cyan);
    }

    /* footer */
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
    }
    @media (max-width: 768px) {
      h1 { font-size: 2.5rem; }
      .grid-services, .cases-row, .stats-grid, .footer-grid {
        grid-template-columns: 1fr;
      }
    }