/* roulang page: index */
:root {
      --primary: #1A1A1A;
      --accent: #E43D2A;
      --accent-hover: #C4311F;
      --bg-white: #FFFFFF;
      --bg-light: #F5F5F7;
      --bg-dark: #1A1A1A;
      --text-primary: #1A1A1A;
      --text-secondary: #666666;
      --text-muted: #999999;
      --text-on-dark: #FFFFFF;
      --border-light: #E5E5E5;
      --border-card: #E5E5E5;
      --shadow-sm: 0 2px 8px rgba(0,0,0,0.04);
      --shadow-md: 0 8px 24px rgba(0,0,0,0.08);
      --shadow-glow: 0 0 20px rgba(228,61,42,0.2);
      --radius-sm: 8px;
      --radius-md: 12px;
      --radius-lg: 16px;
      --font-sans: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --transition: 0.3s ease;
      --container-max: 1200px;
      --nav-height: 72px;
    }

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

    html {
      scroll-behavior: smooth;
      font-size: 16px;
    }

    body {
      font-family: var(--font-sans);
      color: var(--text-primary);
      background: var(--bg-white);
      line-height: 1.7;
      -webkit-font-smoothing: antialiased;
    }

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

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

    button, input {
      font-family: inherit;
      outline: none;
    }

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

    /* 导航栏 */
    .nav {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: var(--bg-white);
      height: var(--nav-height);
      border-bottom: 1px solid rgba(0,0,0,0.04);
      display: flex;
      align-items: center;
      z-index: 1000;
      transition: box-shadow 0.3s;
    }
    .nav.scrolled {
      box-shadow: 0 4px 20px rgba(0,0,0,0.04);
    }
    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
    }
    .logo {
      font-size: 1.6rem;
      font-weight: 800;
      color: var(--primary);
      letter-spacing: -0.5px;
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .logo i {
      color: var(--accent);
      font-size: 1.8rem;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 28px;
      list-style: none;
    }
    .nav-links a {
      font-size: 0.95rem;
      font-weight: 500;
      color: var(--text-primary);
      position: relative;
      padding: 8px 0;
      transition: color 0.2s;
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 50%;
      width: 0;
      height: 2px;
      background: var(--accent);
      transition: width 0.2s ease, left 0.2s ease;
    }
    .nav-links a:hover {
      color: var(--accent);
    }
    .nav-links a:hover::after {
      width: 100%;
      left: 0;
    }
    .nav-cta {
      background: var(--accent);
      color: white;
      padding: 10px 22px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      font-size: 0.9rem;
      transition: background 0.2s, transform 0.1s;
      white-space: nowrap;
    }
    .nav-cta:hover {
      background: var(--accent-hover);
      transform: scale(1.02);
    }
    .hamburger {
      display: none;
      background: none;
      border: none;
      font-size: 1.5rem;
      color: var(--primary);
      cursor: pointer;
    }
    @media (max-width: 767px) {
      .nav-links {
        position: fixed;
        top: 0;
        right: -100%;
        width: 75%;
        max-width: 320px;
        height: 100vh;
        background: white;
        flex-direction: column;
        padding: 100px 30px 40px;
        box-shadow: -8px 0 30px rgba(0,0,0,0.08);
        transition: right 0.3s ease;
        gap: 32px;
        align-items: flex-start;
      }
      .nav-links.active {
        right: 0;
      }
      .nav-links a {
        font-size: 1.2rem;
        font-weight: 600;
      }
      .nav-cta {
        margin-top: 20px;
        align-self: flex-start;
        padding: 12px 32px;
      }
      .hamburger {
        display: block;
        z-index: 1001;
      }
      .close-btn {
        position: absolute;
        top: 20px;
        right: 20px;
        background: none;
        border: none;
        font-size: 1.8rem;
        color: var(--primary);
        cursor: pointer;
      }
    }

    /* 通用板块 */
    section {
      padding: 100px 0;
    }
    @media (max-width: 767px) {
      section {
        padding: 60px 0;
      }
    }
    .section-title {
      font-size: 2.6rem;
      font-weight: 700;
      margin-bottom: 16px;
      letter-spacing: -0.5px;
      line-height: 1.2;
    }
    .section-sub {
      color: var(--text-secondary);
      font-size: 1.1rem;
      margin-bottom: 48px;
      max-width: 700px;
    }

    /* 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;
      color: white;
      margin-top: 0;
      padding-top: var(--nav-height);
    }
    .hero-overlay {
      position: absolute;
      inset: 0;
      background: linear-gradient(90deg, rgba(0,0,0,0.7) 0%, rgba(0,0,0,0.35) 60%);
      z-index: 1;
    }
    .hero-content {
      position: relative;
      z-index: 2;
      max-width: 700px;
    }
    .hero h1 {
      font-size: 3.5rem;
      font-weight: 800;
      line-height: 1.2;
      letter-spacing: -1px;
      margin-bottom: 20px;
    }
    .hero .accent-text {
      color: var(--accent);
    }
    .hero p {
      font-size: 1.25rem;
      font-weight: 300;
      margin-bottom: 32px;
      color: rgba(255,255,255,0.85);
      max-width: 550px;
    }
    .btn-group {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
      align-items: center;
    }
    .btn-primary {
      background: var(--accent);
      color: white;
      padding: 14px 36px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      transition: background 0.2s, transform 0.1s;
      display: inline-block;
    }
    .btn-primary:hover {
      background: var(--accent-hover);
      transform: scale(1.02);
    }
    .btn-ghost {
      background: transparent;
      border: 1.5px solid white;
      color: white;
      padding: 12px 32px;
      border-radius: var(--radius-sm);
      font-weight: 500;
      transition: background 0.2s;
    }
    .btn-ghost:hover {
      background: rgba(255,255,255,0.1);
    }
    .btn-link {
      color: white;
      font-weight: 500;
      border-bottom: 1px solid transparent;
      transition: border-color 0.2s;
    }
    .btn-link:hover {
      border-color: white;
    }

    @media (max-width: 767px) {
      .hero h1 {
        font-size: 2.4rem;
      }
      .hero p {
        font-size: 1rem;
      }
    }

    /* 优势卡片 */
    .grid-4 {
      display: grid;
      grid-template-columns: repeat(4,1fr);
      gap: 24px;
    }
    .advantage-card {
      background: white;
      border: 1px solid var(--border-card);
      border-radius: var(--radius-md);
      padding: 32px 24px;
      transition: all 0.3s;
      text-align: left;
    }
    .advantage-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-md);
    }
    .advantage-icon {
      font-size: 2.4rem;
      color: var(--accent);
      margin-bottom: 16px;
    }
    .advantage-card h4 {
      font-size: 1.25rem;
      margin-bottom: 8px;
    }
    .advantage-card p {
      color: var(--text-secondary);
      font-size: 0.9rem;
    }

    /* 服务非对称 */
    .service-grid {
      display: grid;
      grid-template-columns: 1.5fr 1fr;
      gap: 24px;
    }
    .service-big {
      position: relative;
      border-radius: var(--radius-md);
      overflow: hidden;
      background: white;
      border: 1px solid var(--border-card);
      transition: 0.3s;
    }
    .service-big:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-md);
    }
    .service-big img {
      width: 100%;
      height: 280px;
      object-fit: cover;
      transition: transform 0.3s;
    }
    .service-big:hover img {
      transform: scale(1.03);
    }
    .service-small-group {
      display: flex;
      flex-direction: column;
      gap: 24px;
    }
    .service-small {
      background: white;
      border-radius: var(--radius-md);
      border: 1px solid var(--border-card);
      display: flex;
      transition: 0.3s;
      overflow: hidden;
    }
    .service-small:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-md);
    }
    .service-small img {
      width: 100px;
      height: 100px;
      object-fit: cover;
    }
    .service-info {
      padding: 20px;
    }
    .service-info h4 {
      font-size: 1.2rem;
      margin-bottom: 6px;
    }
    .service-badge {
      display: inline-block;
      background: var(--accent);
      color: white;
      font-size: 0.7rem;
      padding: 2px 10px;
      border-radius: 20px;
      margin-left: 6px;
    }
    .service-card-text {
      padding: 20px;
      background: white;
    }

    @media (max-width: 1023px) {
      .grid-4 { grid-template-columns: repeat(2,1fr); }
      .service-grid { grid-template-columns: 1fr; }
      .service-small { flex-direction: column; }
      .service-small img { width: 100%; height: 140px; }
    }
    @media (max-width: 767px) {
      .grid-4 { grid-template-columns: 1fr; }
    }

    /* 数据见证 */
    .data-section {
      background: var(--bg-light);
    }
    .data-grid {
      display: flex;
      justify-content: space-around;
      text-align: center;
      flex-wrap: wrap;
      gap: 40px;
    }
    .data-item {
      border: 1px dashed var(--border-light);
      padding: 32px 40px;
      border-radius: var(--radius-lg);
      background: white;
      min-width: 180px;
    }
    .data-number {
      font-size: 4rem;
      font-weight: 800;
      color: var(--accent);
      line-height: 1;
    }
    .data-unit {
      font-size: 1.4rem;
      font-weight: 600;
      color: var(--primary);
    }
    .data-label {
      color: var(--text-secondary);
      margin-top: 8px;
    }

    /* 解决方案 */
    .solution-row {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 48px;
      align-items: center;
    }
    .solution-text h3 {
      font-size: 1.8rem;
      margin-bottom: 16px;
    }
    .solution-img {
      border-radius: var(--radius-md);
      overflow: hidden;
    }
    @media (max-width: 767px) {
      .solution-row { grid-template-columns:1fr; }
    }

    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 20px 0;
    }
    .faq-question {
      font-weight: 600;
      font-size: 1.1rem;
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      color: var(--text-secondary);
    }
    .faq-item.active .faq-answer {
      max-height: 150px;
      margin-top: 12px;
    }

    /* CTA dark */
    .cta-dark {
      background: var(--bg-dark);
      color: white;
      text-align: center;
    }
    .cta-dark .btn-primary {
      background: var(--accent);
      padding: 16px 48px;
      font-size: 1.1rem;
    }
    .cta-dark .btn-primary:hover {
      box-shadow: var(--shadow-glow);
    }

    /* Footer */
    .footer {
      background: var(--bg-dark);
      color: rgba(255,255,255,0.7);
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1.5fr;
      gap: 40px;
    }
    .footer a {
      color: rgba(255,255,255,0.6);
    }
    .footer a:hover { color: white; }
    @media (max-width: 767px) {
      .footer-grid { grid-template-columns:1fr; }
    }

    .reveal {
      opacity: 0;
      transform: translateY(24px);
      transition: opacity 0.6s ease, transform 0.6s ease;
    }
    .reveal.visible {
      opacity: 1;
      transform: translateY(0);
    }