/* roulang page: index */
:root {
      --primary: #E60012;
      --primary-hover: #C5000F;
      --dark: #1A1A1A;
      --gold: #C9A84C;
      --bg: #F7F8FA;
      --white: #FFFFFF;
      --text: #2C2C2C;
      --text-secondary: #6B7280;
      --border-light: #E5E7EB;
      --radius-card: 16px;
      --radius-btn: 8px;
      --radius-input: 8px;
      --shadow-card: 0 4px 20px rgba(0,0,0,0.04);
      --shadow-hover: 0 12px 28px rgba(0,0,0,0.08);
      --font-sans: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
      --transition: 200ms ease;
    }

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

    body {
      font-family: var(--font-sans);
      background-color: var(--bg);
      color: var(--text);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }

    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 24px;
    }

    img {
      max-width: 100%;
      display: block;
      height: auto;
    }

    a {
      text-decoration: none;
      color: inherit;
      transition: var(--transition);
    }

    button, .btn {
      cursor: pointer;
      font-family: inherit;
      border: none;
      background: none;
    }

    /* 导航 */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(12px);
      z-index: 100;
      transition: box-shadow 0.25s ease, background 0.25s ease;
      border-bottom: 1px solid transparent;
    }
    .header.scrolled {
      background: rgba(255,255,255,0.98);
      box-shadow: 0 2px 16px rgba(0,0,0,0.04);
      border-bottom: 1px solid var(--border-light);
    }
    .nav-bar {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 72px;
    }
    .logo {
      font-size: 1.7rem;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: 0.5px;
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .logo span {
      color: var(--dark);
      font-weight: 600;
      font-size: 1.5rem;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 2.5rem;
      font-weight: 500;
      color: var(--text);
    }
    .nav-links a {
      position: relative;
      font-size: 1rem;
      padding: 6px 0;
      transition: color 0.2s;
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 1px;
      background: var(--primary);
      transition: width 0.25s ease;
    }
    .nav-links a:hover {
      color: var(--primary);
    }
    .nav-links a:hover::after {
      width: 100%;
    }
    .btn-primary {
      background: var(--primary);
      color: white;
      padding: 12px 24px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 0.95rem;
      transition: background 0.2s, transform 0.1s;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      letter-spacing: 0.3px;
    }
    .btn-primary:hover {
      background: var(--primary-hover);
      transform: translateY(-1px);
    }
    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--primary);
      color: var(--primary);
      padding: 11px 24px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 0.95rem;
      transition: all 0.2s;
      display: inline-flex;
      align-items: center;
      justify-content: center;
    }
    .btn-outline:hover {
      background: var(--primary);
      color: white;
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
    }
    .hamburger span {
      width: 24px;
      height: 2px;
      background: var(--dark);
      border-radius: 2px;
      transition: 0.2s;
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: 72px;
      left: 0;
      width: 100%;
      background: white;
      box-shadow: 0 12px 24px rgba(0,0,0,0.05);
      flex-direction: column;
      padding: 24px;
      gap: 18px;
      z-index: 99;
      transform: translateY(-10px);
      opacity: 0;
      transition: 0.25s;
    }
    .mobile-menu.active {
      display: flex;
      transform: translateY(0);
      opacity: 1;
    }
    .mobile-menu a {
      font-size: 1.1rem;
      font-weight: 500;
      padding: 8px 0;
      border-bottom: 1px solid #f0f0f0;
    }

    /* Hero */
    .hero {
      height: 100vh;
      min-height: 650px;
      background: url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      position: relative;
      display: flex;
      align-items: center;
      justify-content: center;
      text-align: center;
      color: white;
    }
    .hero::before {
      content: '';
      position: absolute;
      inset: 0;
      background: linear-gradient(180deg, rgba(0,0,0,0.3) 0%, rgba(0,0,0,0.65) 100%);
    }
    .hero-content {
      position: relative;
      z-index: 2;
      max-width: 800px;
      margin-top: 20px;
    }
    .hero h1 {
      font-size: clamp(2.4rem, 5vw, 3.8rem);
      font-weight: 700;
      letter-spacing: 0.5px;
      margin-bottom: 1rem;
      line-height: 1.3;
    }
    .hero .subtitle {
      font-size: 1.2rem;
      opacity: 0.9;
      margin-bottom: 2.5rem;
      font-weight: 400;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      justify-content: center;
      flex-wrap: wrap;
    }

    /* 通用板块 */
    section {
      padding: 90px 0;
    }
    .section-title {
      font-size: 2rem;
      font-weight: 700;
      margin-bottom: 1rem;
      color: var(--dark);
      text-align: center;
      letter-spacing: 0.5px;
    }
    .section-sub {
      color: var(--text-secondary);
      text-align: center;
      max-width: 640px;
      margin: 0 auto 48px;
      font-size: 1.05rem;
    }

    /* 核心优势 */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .feature-card {
      background: var(--white);
      padding: 32px 24px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      transition: all 0.25s;
      text-align: center;
      border: 1px solid transparent;
    }
    .feature-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-hover);
      border-color: #f0f0f0;
    }
    .feature-icon {
      font-size: 2.4rem;
      color: var(--primary);
      margin-bottom: 20px;
    }
    .feature-card h3 {
      font-size: 1.3rem;
      margin-bottom: 12px;
      font-weight: 600;
    }
    .feature-card p {
      color: var(--text-secondary);
      font-size: 0.95rem;
    }

    /* 数据条 */
    .stats {
      background: #F0F1F3;
      padding: 64px 0;
    }
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      text-align: center;
      gap: 24px;
    }
    .stat-number {
      font-size: 2.8rem;
      font-weight: 700;
      color: var(--primary);
      line-height: 1.2;
    }
    .stat-label {
      color: var(--text-secondary);
      font-size: 0.95rem;
      margin-top: 6px;
    }

    /* 产品卡片 */
    .products-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 28px;
    }
    .product-card {
      background: white;
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-card);
      transition: 0.25s;
    }
    .product-card:hover {
      box-shadow: var(--shadow-hover);
    }
    .product-img {
      height: 240px;
      background-size: cover;
      background-position: center;
      position: relative;
    }
    .product-img::after {
      content: '';
      position: absolute;
      inset: 0;
      background: rgba(0,0,0,0);
      transition: 0.25s;
    }
    .product-card:hover .product-img::after {
      background: rgba(0,0,0,0.25);
    }
    .product-info {
      padding: 24px;
    }
    .product-info h3 {
      font-size: 1.4rem;
      margin-bottom: 10px;
      font-weight: 600;
    }
    .product-info p {
      color: var(--text-secondary);
      margin-bottom: 16px;
    }
    .text-link {
      color: var(--primary);
      font-weight: 600;
      display: inline-flex;
      align-items: center;
      gap: 4px;
    }
    .text-link:hover {
      text-decoration: underline;
    }

    /* 案例时间线 */
    .timeline {
      display: flex;
      flex-direction: column;
      gap: 32px;
      max-width: 860px;
      margin: 0 auto;
    }
    .timeline-item {
      display: flex;
      gap: 32px;
      align-items: flex-start;
    }
    .year {
      font-weight: 700;
      font-size: 1.6rem;
      color: var(--primary);
      min-width: 70px;
    }
    .timeline-content {
      background: white;
      padding: 20px 24px;
      border-radius: 14px;
      box-shadow: var(--shadow-card);
      flex: 1;
    }

    /* FAQ */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }
    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }
    .faq-question {
      width: 100%;
      text-align: left;
      padding: 20px 8px;
      font-weight: 600;
      font-size: 1.05rem;
      display: flex;
      justify-content: space-between;
      background: transparent;
      border: none;
      cursor: pointer;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s;
      background: #f9fafb;
      border-radius: 10px;
      margin-bottom: 4px;
      padding: 0 16px;
    }
    .faq-answer.open {
      max-height: 200px;
      padding: 16px;
    }

    /* CTA */
    .cta-strip {
      background: var(--dark);
      color: white;
      text-align: center;
      padding: 80px 0;
    }
    .cta-strip h2 {
      font-size: 2.2rem;
      font-weight: 700;
      margin-bottom: 16px;
    }
    .gold-text {
      color: var(--gold);
    }

    /* 页脚 */
    .footer {
      background: #111;
      color: #ccc;
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 32px;
    }
    .footer a {
      color: #aaa;
    }
    .footer a:hover {
      color: white;
    }
    .social-icons {
      display: flex;
      gap: 16px;
      font-size: 1.5rem;
      margin-top: 12px;
    }

    @media (max-width: 1024px) {
      .features-grid { grid-template-columns: repeat(2,1fr); }
      .stats-grid { grid-template-columns: repeat(2,1fr); }
      .products-grid { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr 1fr; }
    }
    @media (max-width: 768px) {
      .nav-links, .header .btn-primary { display: none; }
      .hamburger { display: flex; }
      .features-grid, .stats-grid { grid-template-columns: 1fr; }
      .timeline-item { flex-direction: column; gap: 8px; }
      .footer-grid { grid-template-columns: 1fr; }
      section { padding: 60px 0; }
    }