/* roulang page: index */
/* ----- 设计变量与基础重置 ----- */
    :root {
      --primary-bg: #0A0E17;
      --card-bg: #1A1F2E;
      --accent-cyan: #00F0FF;
      --accent-red: #FF3C38;
      --text-primary: #E8ECF1;
      --text-secondary: #8B95A5;
      --text-white: #FFFFFF;
      --border-light: rgba(255,255,255,0.06);
      --border-focus: rgba(0,240,255,0.25);
      --shadow-card: 0 1px 3px rgba(0,0,0,0.4), 0 4px 16px rgba(0,0,0,0.25);
      --shadow-card-hover: 0 2px 6px rgba(0,0,0,0.5), 0 8px 28px rgba(0,240,255,0.08);
      --radius-lg: 12px;
      --radius-md: 8px;
      --radius-sm: 6px;
      --transition-smooth: 0.25s cubic-bezier(0.25, 0.46, 0.45, 0.94);
      --font-sans: 'Inter', 'SF Pro Display', 'PingFang SC', 'Microsoft YaHei', 'Hiragino Sans GB', 'Noto Sans SC', sans-serif;
      --container-max: 1280px;
      --section-gap: 120px;
      --nav-height: 72px;
    }

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

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

    body {
      font-family: var(--font-sans);
      background-color: var(--primary-bg);
      color: var(--text-primary);
      line-height: 1.75;
      font-size: 16px;
      font-weight: 400;
      -webkit-font-smoothing: antialiased;
      overflow-x: hidden;
    }

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

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

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

    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
      width: 100%;
    }

    /* ----- 导航（沉浸式透明 → 毛玻璃） ----- */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      height: var(--nav-height);
      display: flex;
      align-items: center;
      transition: background 0.3s, backdrop-filter 0.3s, box-shadow 0.3s, height 0.3s;
      background: transparent;
    }

    .site-header.scrolled {
      background: rgba(10, 14, 23, 0.92);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      box-shadow: 0 1px 0 var(--border-light);
      height: 64px;
    }

    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
    }

    .logo {
      font-weight: 700;
      font-size: 1.6rem;
      letter-spacing: 0.02em;
      color: var(--text-white);
      display: flex;
      align-items: center;
    }
    .logo span {
      color: var(--accent-cyan);
    }

    .nav-links {
      display: flex;
      gap: 2rem;
      align-items: center;
      list-style: none;
    }

    .nav-links a {
      font-weight: 500;
      font-size: 0.95rem;
      color: var(--text-secondary);
      position: relative;
      padding: 0.25rem 0;
      transition: color 0.2s;
    }

    .nav-links a:hover,
    .nav-links a.active {
      color: var(--text-white);
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: -2px;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent-cyan);
      transition: width 0.25s ease;
    }
    .nav-links a:hover::after,
    .nav-links a.active::after {
      width: 100%;
    }

    .btn-primary {
      background: var(--accent-cyan);
      color: #0A0E17;
      font-weight: 600;
      padding: 12px 28px;
      border-radius: var(--radius-sm);
      letter-spacing: 0.02em;
      transition: background 0.25s, box-shadow 0.25s;
      display: inline-flex;
      align-items: center;
      justify-content: center;
    }
    .btn-primary:hover {
      background: #33f5ff;
      box-shadow: 0 0 20px rgba(0,240,255,0.5);
    }

    .btn-secondary {
      background: transparent;
      border: 1px solid rgba(255,255,255,0.25);
      color: var(--text-primary);
      font-weight: 500;
      padding: 12px 28px;
      border-radius: var(--radius-sm);
      transition: 0.25s;
    }
    .btn-secondary:hover {
      border-color: var(--accent-cyan);
      color: var(--accent-cyan);
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      background: transparent;
      border: none;
      padding: 4px;
    }
    .hamburger span {
      width: 24px;
      height: 2px;
      background: var(--text-white);
      transition: 0.3s;
    }

    @media (max-width: 768px) {
      .nav-links {
        display: none;
      }
      .hamburger {
        display: flex;
      }
      .mobile-menu {
        position: fixed;
        top: 0;
        right: 0;
        width: 75%;
        max-width: 320px;
        height: 100vh;
        background: var(--card-bg);
        backdrop-filter: blur(20px);
        padding: 2rem;
        flex-direction: column;
        justify-content: center;
        gap: 2rem;
        transform: translateX(100%);
        transition: transform 0.3s ease;
        display: flex;
        z-index: 1100;
      }
      .mobile-menu.open {
        transform: translateX(0);
      }
    }

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

    @media (max-width: 1024px) {
      section {
        padding: 80px 0;
      }
    }
    @media (max-width: 768px) {
      section {
        padding: 60px 0;
      }
    }

    .section-title {
      font-size: clamp(28px, 3.5vw, 44px);
      font-weight: 600;
      letter-spacing: -0.01em;
      color: var(--text-white);
      margin-bottom: 1.5rem;
    }

    /* ----- Hero 双栏 ----- */
    .hero {
      min-height: 90vh;
      display: flex;
      align-items: center;
      padding-top: var(--nav-height);
      background: radial-gradient(circle at 30% 40%, rgba(0,240,255,0.08) 0%, transparent 50%);
    }
    .hero-grid {
      display: grid;
      grid-template-columns: 1.1fr 0.9fr;
      gap: 3rem;
      align-items: center;
    }
    .hero-left .badge {
      display: inline-block;
      border: 1px solid var(--accent-red);
      color: var(--accent-red);
      font-size: 0.8rem;
      padding: 4px 12px;
      border-radius: 20px;
      margin-bottom: 1.5rem;
      letter-spacing: 0.5px;
    }
    .hero-left h1 {
      font-size: clamp(36px, 5vw, 64px);
      font-weight: 700;
      line-height: 1.15;
      letter-spacing: -0.02em;
      color: var(--text-white);
      margin-bottom: 1.5rem;
    }
    .hero-left .sub {
      color: var(--text-secondary);
      margin-bottom: 2rem;
      max-width: 450px;
    }
    .hero-buttons {
      display: flex;
      gap: 1rem;
      flex-wrap: wrap;
    }
    .hero-right {
      background: url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      border-radius: var(--radius-lg);
      min-height: 380px;
      position: relative;
      overflow: hidden;
      box-shadow: var(--shadow-card);
    }
    .hero-right::after {
      content: '';
      position: absolute;
      inset: 0;
      background: rgba(10,14,23,0.5);
    }
    @media (max-width: 768px) {
      .hero-grid {
        grid-template-columns: 1fr;
        text-align: center;
      }
      .hero-buttons {
        justify-content: center;
      }
      .hero-right {
        min-height: 260px;
      }
    }

    /* 亮点网格 3x2 非对称 */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 1.5rem;
      margin-top: 2rem;
    }
    .feature-large {
      grid-row: span 2;
      background: #111827;
      border: 1px solid rgba(0,240,255,0.2);
    }
    .feature-card {
      background: var(--card-bg);
      border-radius: var(--radius-md);
      padding: 1.8rem;
      border: 1px solid var(--border-light);
      transition: var(--transition-smooth);
      display: flex;
      flex-direction: column;
    }
    .feature-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-card-hover);
    }
    .big-number {
      font-size: clamp(40px, 6vw, 72px);
      font-weight: 700;
      color: var(--accent-cyan);
      line-height: 1;
    }
    @media (max-width: 768px) {
      .features-grid {
        grid-template-columns: 1fr;
      }
      .feature-large {
        grid-row: auto;
      }
    }

    /* 案例瀑布流 */
    .cases-masonry {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 1.5rem;
      margin-top: 2rem;
    }
    .case-card {
      background: var(--card-bg);
      border-radius: var(--radius-md);
      overflow: hidden;
      transition: 0.3s;
      border: 1px solid var(--border-light);
    }
    .case-card:nth-child(even) {
      transform: translateY(40px);
    }
    .case-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-card-hover);
    }
    .case-img {
      height: 180px;
      background-size: cover;
      background-position: center;
    }
    .case-content {
      padding: 1.2rem;
    }
    @media (max-width: 768px) {
      .cases-masonry {
        grid-template-columns: 1fr;
      }
      .case-card:nth-child(even) {
        transform: none;
      }
    }

    /* 方案对比三栏 */
    .comparison-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 1.5rem;
      margin-top: 2rem;
    }
    .plan-card {
      background: var(--card-bg);
      border-radius: var(--radius-lg);
      padding: 2rem;
      border: 1px solid var(--border-light);
      transition: 0.3s;
    }
    .plan-card.featured {
      border-top: 4px solid var(--accent-cyan);
      transform: translateY(-8px);
      box-shadow: 0 0 24px rgba(0,240,255,0.12);
    }
    @media (max-width: 768px) {
      .comparison-grid {
        grid-template-columns: 1fr;
      }
      .plan-card.featured {
        transform: none;
      }
    }

    /* FAQ 双栏 */
    .faq-grid {
      display: grid;
      grid-template-columns: 220px 1fr;
      gap: 2rem;
    }
    .faq-tags button {
      background: transparent;
      border: 1px solid var(--border-light);
      color: var(--text-secondary);
      padding: 0.6rem 1rem;
      border-radius: 20px;
      margin-bottom: 0.5rem;
      width: 100%;
      text-align: left;
    }
    .faq-tags button.active {
      background: var(--accent-cyan);
      color: #0A0E17;
      border-color: var(--accent-cyan);
    }
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 1rem 0;
    }
    @media (max-width: 768px) {
      .faq-grid {
        grid-template-columns: 1fr;
      }
    }

    /* CTA 横幅 */
    .cta-banner {
      background: #0f1322;
      text-align: center;
      padding: 4rem 2rem;
      border-radius: var(--radius-lg);
    }

    /* 页脚 */
    .footer-grid {
      display: grid;
      grid-template-columns: 1.5fr 1fr 1fr 1fr;
      gap: 2rem;
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }