/* roulang page: index */
:root {
      --primary-black: #0A0E17;
      --accent-red: #E63946;
      --accent-red-hover: #C1121F;
      --deep-blue: #1D2633;
      --soft-white: #F1FAEE;
      --mint: #A8DADC;
      --warm-orange: #F4A261;
      --text-primary: #FFFFFF;
      --text-secondary: rgba(255,255,255,0.8);
      --text-muted: rgba(255,255,255,0.6);
      --border-subtle: rgba(255,255,255,0.08);
      --border-light: rgba(255,255,255,0.2);
      --card-bg: rgba(29,38,51,0.8);
      --shadow-card: 0 4px 20px rgba(0,0,0,0.25);
      --shadow-hover: 0 10px 30px rgba(0,0,0,0.45);
      --radius-lg: 12px;
      --radius-md: 8px;
      --radius-full: 50px;
      --max-width: 1200px;
      --section-gap: 80px;
      --section-gap-mobile: 48px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    body {
      font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", sans-serif;
      background-color: var(--primary-black);
      color: var(--text-primary);
      line-height: 1.6;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
      overflow-x: hidden;
    }
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 20px;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: opacity 0.2s, color 0.2s;
    }
    button, .btn {
      cursor: pointer;
      font-family: inherit;
      border: none;
      background: none;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      transition: all 0.25s ease;
    }
    h1, h2, h3, h4 {
      font-weight: 700;
      letter-spacing: -0.02em;
    }
    h1 { font-size: clamp(36px, 8vw, 56px); line-height: 1.2; }
    h2 { font-size: clamp(28px, 6vw, 40px); line-height: 1.25; }
    h3 { font-size: clamp(20px, 5vw, 28px); }
    .number-font {
      font-family: "Inter", "Roboto", sans-serif;
      font-weight: 700;
    }

    /* 导航 */
    .main-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 100;
      background: rgba(10,14,23,0.92);
      backdrop-filter: blur(12px);
      border-bottom: 1px solid var(--border-subtle);
    }
    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 64px;
    }
    .logo {
      font-size: 1.8rem;
      font-weight: 700;
      color: var(--accent-red);
      letter-spacing: -0.5px;
      white-space: nowrap;
    }
    .logo span {
      font-size: 0.9rem;
      font-weight: 400;
      color: var(--text-secondary);
      margin-left: 4px;
    }
    .nav-links {
      display: flex;
      gap: 2rem;
      align-items: center;
    }
    .nav-links a {
      font-size: 0.95rem;
      font-weight: 500;
      color: var(--text-secondary);
      padding: 8px 0;
      position: relative;
      border-bottom: 2px solid transparent;
      transition: color 0.2s, border-color 0.2s;
    }
    .nav-links a:hover {
      color: #fff;
      border-bottom-color: var(--accent-red);
    }
    .mobile-nav {
      display: none;
    }

    /* Hero */
    .hero {
      min-height: 90vh;
      display: flex;
      align-items: center;
      background-image: url('/assets/images/backpic/back-1.webp');
      background-size: cover;
      background-position: center 20%;
      position: relative;
      margin-top: 0;
      padding-top: 64px;
    }
    .hero::before {
      content: '';
      position: absolute;
      inset: 0;
      background: linear-gradient(135deg, rgba(10,14,23,0.8) 0%, rgba(10,14,23,0.65) 100%);
      z-index: 1;
    }
    .hero-content {
      position: relative;
      z-index: 2;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 2rem;
      width: 100%;
    }
    .hero-text {
      flex: 1;
    }
    .hero h1 {
      color: #fff;
      margin-bottom: 1.2rem;
    }
    .hero-sub {
      font-size: 1.2rem;
      color: var(--text-secondary);
      margin-bottom: 2rem;
      max-width: 480px;
    }
    .btn-primary {
      background: var(--accent-red);
      color: #fff;
      padding: 0.9rem 2.4rem;
      border-radius: var(--radius-md);
      font-weight: 600;
      font-size: 1.1rem;
      letter-spacing: 0.3px;
      box-shadow: 0 8px 18px rgba(230,57,70,0.3);
      transition: 0.2s;
      border: none;
    }
    .btn-primary:hover {
      background: var(--accent-red-hover);
      transform: scale(1.03);
      box-shadow: 0 12px 24px rgba(198,17,31,0.4);
    }
    .hero-mockup {
      flex: 0 0 260px;
      background: rgba(29,38,51,0.7);
      border-radius: 24px;
      padding: 12px;
      backdrop-filter: blur(8px);
      box-shadow: var(--shadow-card);
    }
    .hero-mockup img {
      border-radius: 16px;
    }

    /* 通用 section */
    section {
      padding: var(--section-gap) 0;
    }

    /* 优势卡片 */
    .features-grid {
      display: grid;
      grid-template-columns: 1.5fr 1fr;
      gap: 24px;
      align-items: start;
    }
    .feature-card {
      background: var(--card-bg);
      backdrop-filter: blur(8px);
      border: 1px solid var(--border-subtle);
      border-radius: var(--radius-lg);
      padding: 2rem;
      transition: all 0.3s;
    }
    .feature-card:hover {
      border-color: var(--mint);
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
    }
    .feature-icon {
      font-size: 2.2rem;
      color: var(--accent-red);
      margin-bottom: 1rem;
    }
    .feature-card h3 {
      margin-bottom: 0.5rem;
    }
    .feature-card p {
      color: var(--text-muted);
      font-size: 0.95rem;
    }

    /* 产品矩阵 */
    .service-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
      gap: 24px;
    }
    .service-item {
      position: relative;
      border-radius: var(--radius-lg);
      overflow: hidden;
      background: var(--deep-blue);
      transition: 0.3s;
      border: 1px solid var(--border-subtle);
    }
    .service-item img {
      aspect-ratio: 16/10;
      object-fit: cover;
      transition: transform 0.4s;
    }
    .service-item:hover img {
      transform: scale(1.05);
    }
    .service-caption {
      position: absolute;
      bottom: 0;
      left: 0;
      right: 0;
      background: rgba(10,14,23,0.8);
      padding: 1rem;
      font-weight: 600;
      backdrop-filter: blur(4px);
    }

    /* 数据计数器 */
    .stats-band {
      background: var(--deep-blue);
      padding: 3rem 0;
      border-radius: var(--radius-lg);
      margin: 2rem 0;
    }
    .stats-flex {
      display: flex;
      justify-content: space-around;
      flex-wrap: wrap;
      text-align: center;
      gap: 2rem;
    }
    .stat-number {
      font-size: 3rem;
      color: var(--warm-orange);
      font-weight: 700;
    }
    .stat-label {
      color: var(--text-muted);
      font-size: 0.9rem;
      margin-top: 0.3rem;
    }

    /* FAQ */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
      background: var(--card-bg);
      border-radius: var(--radius-lg);
      border: 1px solid var(--border-subtle);
      overflow: hidden;
    }
    details {
      border-bottom: 1px solid var(--border-subtle);
      padding: 1.2rem 1.8rem;
      transition: background 0.2s;
    }
    details[open] {
      background: rgba(29,38,51,0.5);
    }
    summary {
      font-weight: 600;
      font-size: 1.1rem;
      cursor: pointer;
      list-style: none;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    summary::after {
      content: '+';
      font-size: 1.5rem;
      color: var(--accent-red);
      transition: transform 0.2s;
    }
    details[open] summary::after {
      content: '−';
      transform: rotate(180deg);
    }
    .faq-answer {
      margin-top: 1rem;
      color: var(--text-secondary);
      line-height: 1.6;
    }

    /* CTA 横幅 */
    .cta-banner {
      background: var(--accent-red);
      text-align: center;
      padding: 4rem 1rem;
      border-radius: var(--radius-lg);
    }
    .cta-banner h2 {
      color: #fff;
      margin-bottom: 1rem;
    }
    .btn-inverse {
      background: #fff;
      color: var(--accent-red);
      padding: 0.8rem 2.8rem;
      border-radius: var(--radius-md);
      font-weight: 700;
    }
    .btn-inverse:hover {
      background: var(--soft-white);
    }

    footer {
      background: var(--primary-black);
      padding: 2rem 0;
      text-align: center;
      color: var(--text-muted);
      font-size: 0.9rem;
    }
    .footer-links {
      display: flex;
      justify-content: center;
      gap: 2rem;
      margin-bottom: 1rem;
    }
    .footer-links a {
      color: var(--text-secondary);
    }

    @media (max-width: 1024px) {
      .hero-content {
        flex-direction: column;
        text-align: center;
      }
      .hero-mockup {
        width: 200px;
      }
      .features-grid {
        grid-template-columns: 1fr;
      }
    }
    @media (max-width: 768px) {
      .desktop-nav {
        display: none;
      }
      .mobile-nav {
        display: flex;
        position: fixed;
        bottom: 16px;
        left: 50%;
        transform: translateX(-50%);
        background: var(--deep-blue);
        border-radius: 40px;
        padding: 0.4rem 1.8rem;
        backdrop-filter: blur(20px);
        z-index: 110;
        gap: 2rem;
        box-shadow: 0 8px 20px rgba(0,0,0,0.6);
      }
      .mobile-nav a {
        display: flex;
        flex-direction: column;
        align-items: center;
        font-size: 0.7rem;
        color: var(--text-secondary);
        padding: 6px 0;
      }
      .mobile-nav i {
        font-size: 1.2rem;
      }
      .hero h1 {
        font-size: 2.5rem;
      }
      section {
        padding: var(--section-gap-mobile) 0;
      }
    }