/* roulang page: index */
:root {
      --bg-deep: #0D0F12;
      --bg-card: #1A1D23;
      --bg-footer: #0A0C0F;
      --accent-red: #F04E30;
      --accent-cyan: #00E5FF;
      --accent-green: #4DFF7C;
      --text-primary: #E8EAED;
      --text-secondary: #8A8F98;
      --border-neon: rgba(0, 229, 255, 0.15);
      --shadow-card: 0 4px 20px rgba(0,0,0,0.6);
      --shadow-hover: 0 12px 28px rgba(0,229,255,0.25);
      --radius-sm: 8px;
      --radius-md: 16px;
      --radius-btn: 4px;
      --space-section: 88px;
      --space-card: 28px;
      --nav-height: 72px;
      --font-sans: 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
      --font-number: 'Inter', 'Roboto', sans-serif;
      transition: background-color 0.2s, border-color 0.2s, color 0.2s;
    }

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

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

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

    .container {
      width: 100%;
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 32px;
    }

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

    a {
      text-decoration: none;
      color: inherit;
      transition: color 0.2s, background 0.2s;
    }

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

    /* 导航栏 */
    .navbar {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      background: rgba(13, 15, 18, 0.92);
      backdrop-filter: blur(14px);
      -webkit-backdrop-filter: blur(14px);
      border-bottom: 1px solid rgba(0, 229, 255, 0.15);
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 0 36px;
      z-index: 1000;
      transition: background 0.25s;
    }

    .logo {
      font-family: var(--font-sans);
      font-weight: 800;
      font-size: 1.8rem;
      letter-spacing: -0.5px;
      color: white;
      display: flex;
      align-items: baseline;
      gap: 4px;
    }
    .logo .accent-red {
      color: var(--accent-red);
      text-shadow: 0 0 12px rgba(240,78,48,0.7);
    }

    .nav-links {
      display: flex;
      gap: 32px;
      align-items: center;
    }
    .nav-links a {
      font-weight: 500;
      color: var(--text-secondary);
      font-size: 1rem;
      position: relative;
      padding: 6px 0;
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent-cyan);
      box-shadow: 0 0 8px var(--accent-cyan);
      transition: width 0.25s ease;
    }
    .nav-links a:hover {
      color: white;
    }
    .nav-links a:hover::after,
    .nav-links a.active::after {
      width: 100%;
    }
    .nav-links a.active {
      color: white;
    }
    .nav-cta {
      background: var(--accent-red);
      color: white;
      font-weight: 700;
      padding: 10px 24px;
      border-radius: var(--radius-btn);
      font-size: 0.95rem;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      box-shadow: 0 4px 14px rgba(240,78,48,0.5);
      transition: background 0.2s, box-shadow 0.25s;
      margin-left: 16px;
      white-space: nowrap;
    }
    .nav-cta:hover {
      background: #D03A20;
      box-shadow: 0 0 20px rgba(240,78,48,0.8);
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 6px;
      cursor: pointer;
    }
    .hamburger span {
      width: 28px;
      height: 2.5px;
      background: var(--accent-cyan);
      border-radius: 2px;
      transition: 0.25s;
    }

    /* Hero */
    .hero {
      min-height: 100vh;
      display: flex;
      align-items: center;
      background: radial-gradient(circle at 20% 30%, rgba(0,229,255,0.08) 0%, rgba(13,15,18,0.98) 80%),
                  url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      position: relative;
      padding-top: var(--nav-height);
    }
    .hero-content {
      display: grid;
      grid-template-columns: 1.1fr 0.9fr;
      gap: 60px;
      align-items: center;
      width: 100%;
    }
    .hero-text h1 {
      font-size: clamp(2.6rem, 6vw, 4.4rem);
      font-weight: 800;
      letter-spacing: -0.02em;
      line-height: 1.15;
      color: white;
    }
    .hero-text h1 .highlight {
      color: var(--accent-red);
      text-shadow: 0 0 18px rgba(240,78,48,0.9);
      display: inline-block;
    }
    .hero-text p {
      font-size: 1.2rem;
      max-width: 580px;
      color: var(--text-secondary);
      margin: 24px 0 32px;
      font-weight: 400;
    }
    .hero-buttons {
      display: flex;
      gap: 20px;
      flex-wrap: wrap;
    }
    .btn-primary {
      background: var(--accent-red);
      color: white;
      padding: 16px 40px;
      font-weight: 700;
      font-size: 1.1rem;
      text-transform: uppercase;
      border-radius: var(--radius-btn);
      box-shadow: 0 8px 24px rgba(240,78,48,0.55);
      transition: 0.2s;
      letter-spacing: 0.5px;
    }
    .btn-primary:hover {
      background: #C8371C;
      box-shadow: 0 0 28px rgba(240,78,48,0.9);
    }
    .btn-outline {
      border: 1px solid var(--accent-cyan);
      color: var(--accent-cyan);
      padding: 16px 40px;
      font-weight: 700;
      font-size: 1.1rem;
      text-transform: uppercase;
      border-radius: var(--radius-btn);
      background: transparent;
      transition: 0.2s;
    }
    .btn-outline:hover {
      background: rgba(0,229,255,0.12);
      box-shadow: 0 0 24px rgba(0,229,255,0.5);
      color: white;
    }
    .hero-visual {
      display: flex;
      justify-content: center;
      align-items: center;
    }
    .hero-visual img {
      border-radius: var(--radius-md);
      box-shadow: 0 20px 40px rgba(0,0,0,0.8), 0 0 25px rgba(0,229,255,0.25);
      border: 1px solid rgba(0,229,255,0.2);
    }

    section {
      padding: var(--space-section) 0;
    }

    .section-head {
      margin-bottom: 56px;
    }
    .section-head h2 {
      font-size: 2.5rem;
      font-weight: 800;
      color: white;
      letter-spacing: -0.02em;
    }
    .section-head p {
      color: var(--text-secondary);
      font-size: 1.15rem;
      margin-top: 12px;
    }

    /* 核心优势 不对称网格 */
    .features-grid {
      display: grid;
      grid-template-columns: 1.4fr 1fr 1.2fr;
      gap: 28px;
    }
    .feature-card {
      background: var(--bg-card);
      border: 1px solid var(--border-neon);
      border-radius: var(--radius-md);
      padding: var(--space-card);
      transition: 0.25s;
      position: relative;
    }
    .feature-card:hover {
      box-shadow: var(--shadow-hover);
      border-color: rgba(0,229,255,0.5);
      transform: translateY(-4px);
    }
    .feature-icon {
      font-size: 2.8rem;
      color: var(--accent-cyan);
      margin-bottom: 18px;
      text-shadow: 0 0 8px var(--accent-cyan);
    }
    .feature-card h3 {
      font-size: 1.6rem;
      font-weight: 700;
      color: white;
    }
    .feature-card p {
      color: var(--text-secondary);
      margin-top: 12px;
    }
    .feature-card.large {
      grid-row: span 2;
      display: flex;
      flex-direction: column;
      justify-content: center;
    }

    /* 服务分组 */
    .service-row {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 48px;
      align-items: center;
      margin-bottom: 72px;
    }
    .service-text h3 {
      font-size: 2rem;
      font-weight: 700;
      color: white;
    }
    .service-text p {
      color: var(--text-secondary);
      margin: 16px 0;
    }
    .service-img img {
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-card);
      border: 1px solid rgba(0,229,255,0.2);
    }

    /* 使用场景网格 */
    .scenarios-grid {
      display: grid;
      grid-template-columns: repeat(2,1fr);
      gap: 28px;
    }
    .scenario-card {
      background: var(--bg-card);
      border-radius: var(--radius-md);
      padding: 22px;
      border-left: 4px solid var(--accent-red);
      transition: 0.2s;
    }
    .scenario-card:hover {
      border-left-color: var(--accent-cyan);
      box-shadow: 0 0 22px rgba(0,229,255,0.25);
    }

    /* 案例数字 */
    .cases-stats {
      display: flex;
      flex-wrap: wrap;
      gap: 40px;
      justify-content: space-between;
    }
    .stat-item {
      font-family: var(--font-number);
      font-size: 3.2rem;
      font-weight: 800;
      color: var(--accent-cyan);
      text-shadow: 0 0 15px rgba(0,229,255,0.7);
    }

    /* FAQ */
    .faq-item {
      background: var(--bg-card);
      border-left: 4px solid var(--accent-red);
      margin-bottom: 14px;
      border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
      padding: 0 22px;
      transition: 0.2s;
    }
    .faq-question {
      font-weight: 700;
      color: white;
      padding: 18px 0;
      display: flex;
      justify-content: space-between;
      cursor: pointer;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      color: var(--text-secondary);
      transition: max-height 0.3s ease;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-bottom: 18px;
    }

    /* CTA */
    .cta-block {
      background: #0A0C0F;
      text-align: center;
      padding: 80px 24px;
      border-top: 1px solid var(--accent-cyan);
    }

    /* Footer */
    .footer {
      background: var(--bg-footer);
      padding: 60px 0 32px;
      border-top: 1px solid rgba(0,229,255,0.2);
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 32px;
    }

    @media (max-width: 1024px) {
      .features-grid { grid-template-columns: 1fr 1fr; }
      .hero-content { grid-template-columns: 1fr; }
    }
    @media (max-width: 768px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .features-grid, .scenarios-grid, .service-row { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr 1fr; }
    }