/* roulang page: index */
/* ----- 设计宪法变量 & 全局重置 ----- */
    :root {
      --deep-space: #0A0E17;
      --carbon-black: #12171F;
      --card-bg: #1A202A;
      --footer-bg: #080B12;
      --electric-cyan: #00F0FF;
      --competition-red: #FF4655;
      --text-primary: #E8ECF0;
      --text-secondary: #B0B8C1;
      --text-muted: #6B7280;
      --border-glow: rgba(0,240,255,0.08);
      --border-hover-glow: rgba(0,240,255,0.35);
      --radius-sharp: 4px 0 4px 0;
      --radius-sm: 8px;
      --radius-card: 12px;
      --shadow-card: 0 10px 25px -8px rgba(0,0,0,0.5);
      --shadow-hover: 0 0 22px rgba(0,240,255,0.25);
      --font-main: "PingFang SC", "Microsoft YaHei", "Inter", system-ui, -apple-system, sans-serif;
      --container-max: 1280px;
      --section-gap: 130px;
      --card-gap: 24px;
      --transition-fast: 0.2s ease;
      --transition-smooth: 0.3s cubic-bezier(0.23, 1, 0.32, 1);
    }

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

    html {
      scroll-behavior: smooth;
      scroll-padding-top: 90px;
    }

    body {
      background-color: var(--deep-space);
      color: var(--text-secondary);
      font-family: var(--font-main);
      line-height: 1.65;
      text-rendering: optimizeLegibility;
      -webkit-font-smoothing: antialiased;
    }

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

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

    button, .btn {
      cursor: pointer;
      font-family: inherit;
      border: none;
      background: none;
      transition: all var(--transition-smooth);
    }

    ul, ol {
      list-style: none;
    }

    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 20px;
    }

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

    .section-bg-alt {
      background-color: var(--carbon-black);
    }

    /* 标题层级 */
    h2.section-title {
      color: var(--text-primary);
      font-size: clamp(2rem, 4.5vw, 2.8rem);
      font-weight: 700;
      letter-spacing: -0.02em;
      text-align: center;
      margin-bottom: 10px;
      position: relative;
    }
    .section-desc {
      text-align: center;
      color: var(--text-secondary);
      max-width: 700px;
      margin: 0 auto 55px;
      font-size: 1.1rem;
    }

    /* ----- 导航 (沉浸式) ----- */
    .header {
      position: sticky;
      top: 0;
      left: 0;
      z-index: 99;
      background: rgba(10,14,23,0.88);
      backdrop-filter: blur(14px);
      -webkit-backdrop-filter: blur(14px);
      border-bottom: 1px solid rgba(0,240,255,0.12);
    }
    .header .container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 74px;
      gap: 20px;
    }
    .logo {
      font-size: 1.7rem;
      font-weight: 900;
      color: var(--text-primary);
      letter-spacing: -0.01em;
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .logo span {
      color: var(--electric-cyan);
      background: linear-gradient(135deg, #00F0FF 0%, #3db5ff 90%);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
    }
    .nav-menu {
      display: flex;
      align-items: center;
      gap: 34px;
    }
    .nav-link {
      color: var(--text-secondary);
      font-weight: 500;
      font-size: 0.95rem;
      letter-spacing: 0.5px;
      position: relative;
    }
    .nav-link:hover {
      color: var(--electric-cyan);
    }
    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -6px;
      left: 0;
      width: 0%;
      height: 2px;
      background: var(--electric-cyan);
      transition: width var(--transition-fast);
      box-shadow: 0 0 8px var(--electric-cyan);
    }
    .nav-link:hover::after {
      width: 100%;
    }
    .nav-cta {
      background: var(--electric-cyan);
      color: var(--deep-space);
      font-weight: 700;
      padding: 10px 26px;
      border-radius: var(--radius-sharp);
      display: inline-block;
      font-size: 0.9rem;
      letter-spacing: 0.5px;
      margin-left: 12px;
    }
    .nav-cta:hover {
      background: var(--competition-red);
      color: white;
      box-shadow: 0 0 18px rgba(255,70,85,0.55);
    }
    .hamburger {
      display: none;
      font-size: 28px;
      color: var(--electric-cyan);
    }
    @media (max-width: 850px) {
      .nav-menu {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100vh;
        background: var(--deep-space);
        flex-direction: column;
        justify-content: center;
        gap: 40px;
        transform: translateX(-100%);
        transition: 0.35s ease;
        z-index: 100;
      }
      .nav-menu.active {
        transform: translateX(0);
      }
      .hamburger {
        display: block;
        z-index: 101;
      }
      .nav-cta {
        margin: 10px 0;
      }
    }

    /* ----- 首屏 Hero ----- */
    .hero {
      padding: 40px 0 60px;
      background-color: var(--deep-space);
      background-image: url('/assets/images/backpic/back-1.webp');
      background-size: cover;
      background-position: center 20%;
      position: relative;
    }
    .hero::after {
      content: '';
      position: absolute;
      inset:0;
      background: radial-gradient(circle at 30% 30%, rgba(0,240,255,0.06) 0%, rgba(10,14,23,0.8) 90%);
    }
    .hero .container {
      position: relative;
      z-index: 2;
      display: flex;
      align-items: center;
      gap: 30px;
      flex-wrap: wrap;
    }
    .hero-text {
      flex: 1 1 500px;
    }
    .hero-visual {
      flex: 1 1 400px;
      background: rgba(0,240,255,0.02);
      border-radius: 16px;
      overflow: hidden;
      border: 1px solid rgba(0,240,255,0.1);
    }
    h1.hero-title {
      color: white;
      font-size: clamp(2.9rem, 7vw, 4.8rem);
      font-weight: 900;
      line-height: 1.1;
      margin-bottom: 20px;
      letter-spacing: -0.02em;
    }
    h1.hero-title i {
      color: var(--electric-cyan);
      font-style: normal;
    }
    .hero-sub {
      font-size: 1.2rem;
      color: #d1d5db;
      margin-bottom: 32px;
      max-width: 540px;
    }
    .btn-group {
      display: flex;
      flex-wrap: wrap;
      gap: 18px;
    }
    .btn-primary {
      background: var(--electric-cyan);
      color: #0A0E17;
      font-weight: bold;
      padding: 14px 38px;
      border-radius: var(--radius-sharp);
      font-size: 1rem;
      letter-spacing: 0.5px;
    }
    .btn-primary:hover {
      background: #2bffff;
      box-shadow: 0 0 20px rgba(0,240,255,0.55);
    }
    .btn-outline {
      border: 1px solid var(--electric-cyan);
      color: var(--electric-cyan);
      padding: 14px 34px;
      border-radius: var(--radius-sharp);
      font-weight: 600;
    }
    .btn-outline:hover {
      background: rgba(0,240,255,0.08);
      border-color: white;
    }

    /* 卡片网格 */
    .features-grid, .service-grid, .scenario-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
      gap: var(--card-gap);
    }
    .card {
      background: var(--card-bg);
      border: 1px solid var(--border-glow);
      border-radius: var(--radius-card);
      padding: 28px 24px;
      transition: all 0.25s;
    }
    .card:hover {
      transform: translateY(-8px);
      border-color: rgba(0,240,255,0.3);
      box-shadow: var(--shadow-hover);
    }
    .card-icon {
      font-size: 2.5rem;
      color: var(--electric-cyan);
      margin-bottom: 20px;
    }
    .card h3 {
      color: white;
      font-weight: 650;
      font-size: 1.4rem;
    }

    /* 案例 with 数字 */
    .case-stats {
      display: flex;
      gap: 35px;
      flex-wrap: wrap;
      justify-content: center;
    }
    .stat-number {
      font-weight: 800;
      font-size: 2.6rem;
      color: var(--electric-cyan);
    }

    /* FAQ */
    .faq-item {
      border-bottom: 1px solid rgba(255,255,255,0.12);
      padding: 18px 0;
    }
    .faq-question {
      font-weight: 600;
      color: white;
      display: flex;
      justify-content: space-between;
    }

    /* 其他省略手写样式保证现代感 */
    footer a:hover { color: var(--electric-cyan); }