/* roulang page: index */
/* ----- DESIGN SYSTEM & RESET ----- */
    :root {
      --primary: #6C3CF0;
      --primary-hover: #7B4FF2;
      --accent: #00F0C8;
      --accent-glow: rgba(0,240,200,0.25);
      --bg-deep: #0A0A0F;
      --bg-card: #F4F4F7;
      --text-on-dark: #FFFFFF;
      --text-primary: #1A1A1A;
      --text-secondary: #6B6B7B;
      --border-light: rgba(255,255,255,0.1);
      --shadow-sm: 0 4px 24px rgba(108,60,240,0.08);
      --shadow-hover: 0 14px 28px rgba(108,60,240,0.14);
      --radius-card: 8px;
      --radius-button: 4px;
      --transition: 0.3s cubic-bezier(0.24, 0.52, 0.22, 1);
    }

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

    body {
      font-family: "Helvetica Neue", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
      line-height: 1.7;
      color: var(--text-primary);
      background-color: #ffffff;
      overflow-x: hidden;
    }

    .container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 24px;
    }

    h1, h2, h3, .nav-link, button, .cta-button, .stats-number {
      font-feature-settings: "kern";
    }

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

    a {
      text-decoration: none;
      color: inherit;
    }

    /* ----- TYPOGRAPHY ----- */
    .heading-xl {
      font-family: "Helvetica Neue", "PingFang SC", "Source Han Sans CN", sans-serif;
      font-weight: 900;
      letter-spacing: -0.02em;
      line-height: 1.1;
      color: var(--text-on-dark);
    }

    .section-title {
      font-size: clamp(2rem, 4vw, 3rem);
      font-weight: 700;
      display: flex;
      align-items: center;
      gap: 12px;
      margin-bottom: 2.5rem;
      color: var(--text-primary);
    }

    .section-title .accent-line {
      display: inline-block;
      width: 48px;
      height: 4px;
      background: linear-gradient(90deg, var(--primary) 0%, var(--accent) 100%);
    }

    .section-title .eng-sub {
      font-size: 0.8rem;
      font-weight: 400;
      color: var(--text-secondary);
      text-transform: uppercase;
      letter-spacing: 2px;
      margin-left: 4px;
    }

    /* ----- NAVIGATION (PC + MOBILE CAPSULE) ----- */
    .navbar {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 999;
      background: rgba(10,10,15,0.7);
      backdrop-filter: blur(16px);
      -webkit-backdrop-filter: blur(16px);
      border-bottom: 1px solid rgba(255,255,255,0.06);
      transition: background 0.35s ease;
    }

    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      height: 72px;
    }

    .logo {
      font-size: 1.8rem;
      font-weight: 800;
      color: white;
      letter-spacing: -0.5px;
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .logo i {
      color: var(--accent);
      font-size: 1.7rem;
    }

    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
      list-style: none;
    }

    .nav-link {
      color: #ddd;
      font-weight: 500;
      font-size: 0.95rem;
      transition: color var(--transition);
      border-bottom: 2px solid transparent;
      padding: 6px 0;
    }

    .nav-link:hover,
    .nav-link.active {
      color: var(--accent);
      border-bottom-color: var(--accent);
    }

    .btn-nav-cta {
      background: var(--primary);
      color: white;
      padding: 10px 24px;
      border-radius: var(--radius-button);
      font-weight: 600;
      margin-left: 12px;
      transition: all var(--transition);
    }

    .btn-nav-cta:hover {
      background: var(--accent);
      color: var(--bg-deep);
    }

    /* Mobile bottom navigation */
    .mobile-bottom-nav {
      display: none;
    }

    @media (max-width: 768px) {
      .desktop-nav {
        display: none;
      }
      .mobile-bottom-nav {
        display: flex;
        position: fixed;
        bottom: 0;
        left: 0;
        width: 100%;
        background: var(--bg-deep);
        backdrop-filter: blur(20px);
        border-top: 1px solid rgba(255,255,255,0.08);
        justify-content: space-around;
        align-items: center;
        height: 64px;
        z-index: 1000;
        padding: 0 8px;
      }
      .mobile-nav-item {
        display: flex;
        flex-direction: column;
        align-items: center;
        color: #aaa;
        font-size: 0.7rem;
        transition: 0.2s;
        flex: 1;
      }
      .mobile-nav-item i {
        font-size: 1.3rem;
        margin-bottom: 2px;
      }
      .mobile-nav-item.active, .mobile-nav-item:active {
        color: var(--accent);
      }
    }

    /* ----- HERO SECTION (背景图占位/覆盖深色) ----- */
    .hero-section {
      background: linear-gradient(145deg, #0A0A0F 0%, #1C103F 60%, #0A0A0F 100%);
      position: relative;
      min-height: 100vh;
      display: flex;
      align-items: center;
      overflow: hidden;
    }

    .hero-bg-img {
      position: absolute;
      right: 0;
      top: 0;
      width: 55%;
      height: 100%;
      background-image: url('/assets/images/backpic/back-1.webp');
      background-size: cover;
      background-position: left center;
      opacity: 0.65;
      mask-image: linear-gradient(to left, rgba(0,0,0,0.8) 20%, transparent 95%);
      -webkit-mask-image: linear-gradient(to left, rgba(0,0,0,0.8) 20%, transparent 95%);
    }

    .hero-grid {
      display: flex;
      align-items: center;
      position: relative;
      z-index: 2;
      width: 100%;
    }

    .hero-text {
      flex: 0 0 55%;
      padding-right: 20px;
    }
    .hero-label {
      color: var(--accent);
      font-weight: 600;
      letter-spacing: 3px;
      font-size: 0.9rem;
      border-left: 4px solid var(--accent);
      padding-left: 15px;
      margin-bottom: 16px;
    }

    .hero-text h1 {
      font-size: clamp(2.8rem, 6vw, 4rem);
      font-weight: 800;
      line-height: 1.15;
      margin-bottom: 20px;
      color: white;
    }
    .hero-text .sub {
      font-size: 1.2rem;
      color: #c2c2d0;
      margin-bottom: 36px;
      max-width: 480px;
    }

    .hero-cta-group {
      display: flex;
      gap: 18px;
      flex-wrap: wrap;
    }

    .btn-primary {
      background: var(--primary);
      color: white;
      padding: 14px 36px;
      border-radius: var(--radius-button);
      font-weight: 700;
      border: none;
      cursor: pointer;
      transition: all var(--transition);
      font-size: 1rem;
    }
    .btn-primary:hover {
      background: var(--accent);
      color: #0A0A0F;
      transform: scale(1.03);
    }

    .btn-outline {
      background: transparent;
      border: 1px solid var(--primary);
      color: white;
      padding: 14px 32px;
      border-radius: var(--radius-button);
      font-weight: 600;
      transition: all var(--transition);
    }
    .btn-outline:hover {
      background: var(--primary);
      border-color: var(--primary);
    }

    @media (max-width: 768px) {
      .hero-grid {
        flex-direction: column;
      }
      .hero-text {
        flex: auto;
        padding-right: 0;
        text-align: center;
        margin-top: 80px;
      }
      .hero-bg-img {
        width: 100%;
        opacity: 0.3;
      }
      .hero-text h1 {
        font-size: 2.4rem;
      }
    }

    /* ----- sections blocks ----- */
    section {
      padding: 100px 0;
    }
    @media (max-width: 768px) {
      section {
        padding: 64px 0;
      }
    }

    .card-grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 32px;
    }

    .advantage-card {
      background: var(--bg-card);
      border-radius: var(--radius-card);
      padding: 40px 24px;
      box-shadow: var(--shadow-sm);
      transition: all var(--transition);
      border-bottom: 3px solid transparent;
    }
    .advantage-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
      border-bottom-color: var(--accent);
    }
    .advantage-icon {
      font-size: 2.8rem;
      color: var(--accent);
      margin-bottom: 20px;
    }
    .stats-number {
      font-size: 3rem;
      font-weight: 800;
      color: var(--primary);
      font-family: 'Space Grotesk', monospace;
    }

    /* 实时数据区块 */
    .stats-bg {
      background: #0A0A0F;
      color: white;
    }
    .stats-flex {
      display: flex;
      justify-content: space-around;
      text-align: center;
      flex-wrap: wrap;
      gap: 30px;
    }

    /* 解决方案左右交替 */
    .solution-row {
      display: flex;
      align-items: center;
      gap: 60px;
      margin-bottom: 80px;
    }
    .solution-row.reverse {
      flex-direction: row-reverse;
    }
    .solution-img {
      flex: 1;
      border-radius: 12px;
      overflow: hidden;
    }
    .solution-img img {
      width: 100%;
      height: auto;
    }

    /* 合作案例瀑布流 */
    .case-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 24px;
    }
    .case-card {
      position: relative;
      border-radius: 12px;
      overflow: hidden;
      transition: all 0.3s ease;
    }
    .case-card img {
      width: 100%;
      display: block;
    }
    .case-overlay {
      position: absolute;
      top: 0; left: 0; width: 100%; height: 100%;
      background: linear-gradient(180deg, rgba(108,60,240,0.7) 0%, rgba(0,240,200,0.5) 100%);
      opacity: 0;
      transition: 0.3s;
      display: flex;
      align-items: center;
      justify-content: center;
      color: white;
      font-weight: bold;
    }
    .case-card:hover .case-overlay {
      opacity: 1;
    }

    /* FAQ */
    .faq-item {
      border-bottom: 1px solid #e0e0e0;
      padding: 20px 0;
    }
    .faq-question {
      font-weight: 700;
      display: flex;
      align-items: center;
      gap: 12px;
      cursor: pointer;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
    }

    /* CTA 横幅 */
    .cta-banner {
      background: linear-gradient(105deg, #6C3CF0 0%, #0A0A0F 90%);
      transform: skewY(-2deg);
      margin: 60px 0;
      padding: 70px 0;
    }
    .cta-banner-content {
      transform: skewY(2deg);
      text-align: center;
      color: white;
    }

    footer {
      background: #0A0A0F;
      color: #ccc;
      padding: 60px 0 30px;
    }

    @media (max-width: 768px) {
      .card-grid-3, .case-grid {
        grid-template-columns: 1fr;
      }
    }