/* roulang page: index */
:root {
      --primary: #C8A45C;
      --primary-dark: #B08F42;
      --primary-light: rgba(200, 164, 92, 0.15);
      --success: #00B578;
      --warning: #FF9F0A;
      --error: #FA5151;
      --bg: #F5F6FA;
      --surface: #FFFFFF;
      --dark-bg: #2A2A2A;
      --text-main: #1F2329;
      --text-secondary: #86909C;
      --text-light: #B0B8C1;
      --text-on-primary: #FFFFFF;
      --border: #E5E8ED;
      --border-light: #EAECF0;
      --radius: 12px;
      --radius-sm: 8px;
      --radius-lg: 16px;
      --radius-btn: 8px;
      --shadow-card: 0 4px 20px rgba(0,0,0,0.04), 0 1px 3px rgba(0,0,0,0.02);
      --shadow-hover: 0 12px 28px rgba(0,0,0,0.08), 0 2px 8px rgba(0,0,0,0.04);
      --transition: 250ms ease-out;
      --container: 1140px;
      --header-height: 64px;
    }

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

    html {
      scroll-behavior: smooth;
      scroll-padding-top: var(--header-height);
    }

    body {
      font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      background-color: var(--bg);
      color: var(--text-main);
      line-height: 1.6;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }

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

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

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

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

    @media (max-width: 767px) {
      .container {
        padding: 0 16px;
      }
    }

    /* header / nav */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--header-height);
      background: rgba(255,255,255,0.72);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      box-shadow: 0 1px 4px rgba(0,0,0,0.02);
      z-index: 1000;
      transition: background 0.3s, box-shadow 0.3s;
    }

    .site-header.scrolled {
      background: rgba(255,255,255,0.92);
      box-shadow: 0 2px 12px rgba(0,0,0,0.06);
    }

    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 100%;
    }

    .logo a {
      display: flex;
      align-items: baseline;
      gap: 6px;
      font-weight: 700;
      font-size: 22px;
      color: var(--text-main);
    }

    .logo .brand {
      color: var(--primary-dark);
    }

    .logo .domain {
      font-size: 12px;
      font-weight: 400;
      color: var(--text-secondary);
      margin-left: 2px;
    }

    .nav-links {
      display: flex;
      gap: 28px;
      align-items: center;
      list-style: none;
    }

    .nav-links a {
      font-size: 15px;
      font-weight: 500;
      color: var(--text-main);
      position: relative;
      padding: 8px 0;
    }

    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 100%;
      height: 2px;
      background: var(--primary);
      transform: scaleX(0);
      transition: transform var(--transition);
      border-radius: 1px;
    }

    .nav-links a:hover::after,
    .nav-links a.active::after {
      transform: scaleX(1);
    }

    .menu-toggle {
      display: none;
      flex-direction: column;
      gap: 5px;
      background: none;
      border: none;
      padding: 8px;
    }

    .menu-toggle span {
      display: block;
      width: 24px;
      height: 2px;
      background: var(--text-main);
      border-radius: 2px;
      transition: var(--transition);
    }

    @media (max-width: 991px) {
      .menu-toggle {
        display: flex;
      }
      .nav-links {
        position: fixed;
        top: var(--header-height);
        left: 0;
        width: 100%;
        background: rgba(255,255,255,0.98);
        backdrop-filter: blur(12px);
        flex-direction: column;
        padding: 32px 24px;
        gap: 20px;
        transform: translateY(-120%);
        transition: transform 0.35s ease;
        box-shadow: 0 8px 24px rgba(0,0,0,0.06);
        z-index: 999;
      }
      .nav-links.open {
        transform: translateY(0);
      }
      .nav-links a {
        font-size: 18px;
        padding: 12px 0;
        display: block;
      }
    }

    /* sections */
    section {
      padding: 100px 0;
    }

    @media (max-width: 767px) {
      section {
        padding: 60px 0;
      }
    }

    .section-title {
      font-size: 28px;
      font-weight: 600;
      line-height: 1.4;
      margin-bottom: 12px;
      color: var(--text-main);
    }

    .section-sub {
      font-size: 16px;
      color: var(--text-secondary);
      margin-bottom: 48px;
      max-width: 640px;
    }

    .text-center {
      text-align: center;
    }

    .mx-auto {
      margin-left: auto;
      margin-right: auto;
    }

    /* buttons */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 12px 28px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 15px;
      transition: all var(--transition);
      gap: 8px;
    }

    .btn-primary {
      background: var(--primary);
      color: var(--text-on-primary);
    }

    .btn-primary:hover {
      background: var(--primary-dark);
      box-shadow: 0 8px 18px rgba(200,164,92,0.25);
    }

    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--primary);
      color: var(--primary-dark);
    }

    .btn-outline:hover {
      background: var(--primary-light);
    }

    .btn-lg {
      padding: 14px 36px;
      font-size: 17px;
      border-radius: 50px;
    }

    /* hero */
    .hero {
      padding: 140px 0 100px;
      display: flex;
      align-items: center;
      background: var(--bg);
    }

    .hero .container {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 48px;
      align-items: center;
    }

    .hero h1 {
      font-size: 40px;
      font-weight: 700;
      line-height: 1.3;
      color: var(--text-main);
      margin-bottom: 16px;
    }

    .hero .hero-desc {
      font-size: 16px;
      color: var(--text-secondary);
      margin-bottom: 32px;
    }

    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }

    .hero-image {
      background: linear-gradient(135deg, rgba(200,164,92,0.15) 0%, rgba(200,164,92,0.05) 100%);
      border-radius: var(--radius-lg);
      overflow: hidden;
      display: flex;
      align-items: center;
      justify-content: center;
      aspect-ratio: 4/3;
    }

    .hero-image img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      border-radius: var(--radius-lg);
    }

    @media (max-width: 991px) {
      .hero .container {
        grid-template-columns: 1fr;
        text-align: center;
      }
      .hero h1 {
        font-size: 32px;
      }
      .hero-buttons {
        justify-content: center;
      }
      .hero-image {
        order: -1;
        max-width: 400px;
        margin: 0 auto;
      }
    }

    /* services irregular layout */
    .services-grid {
      display: grid;
      grid-template-columns: 1fr 1fr 1fr;
      gap: 24px;
    }

    .service-card {
      background: var(--surface);
      border-radius: var(--radius);
      padding: 28px 24px;
      box-shadow: var(--shadow-card);
      transition: all var(--transition);
      display: flex;
      flex-direction: column;
      border-left: 4px solid transparent;
    }

    .service-card.featured {
      grid-row: span 2;
      border-left: 4px solid var(--primary);
      padding: 36px 28px;
    }

    .service-card:hover {
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
    }

    .service-icon {
      font-size: 32px;
      color: var(--primary);
      margin-bottom: 16px;
    }

    .service-card h3 {
      font-size: 20px;
      font-weight: 600;
      margin-bottom: 8px;
    }

    .service-card p {
      font-size: 14px;
      color: var(--text-secondary);
      margin-bottom: 16px;
      flex: 1;
    }

    .service-link {
      font-weight: 600;
      font-size: 14px;
      color: var(--primary-dark);
      align-self: flex-start;
    }

    @media (max-width: 991px) {
      .services-grid {
        grid-template-columns: 1fr 1fr;
      }
    }

    @media (max-width: 767px) {
      .services-grid {
        grid-template-columns: 1fr;
      }
      .service-card.featured {
        grid-row: auto;
      }
    }

    /* data numbers */
    .data-section {
      background: var(--surface);
      border-top: 1px solid var(--border-light);
    }

    .data-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 32px;
      text-align: center;
    }

    .data-item .number {
      font-size: 48px;
      font-weight: 700;
      color: var(--primary);
      line-height: 1.2;
    }

    .data-item .label {
      font-size: 14px;
      color: var(--text-secondary);
      margin-top: 8px;
    }

    @media (max-width: 767px) {
      .data-grid {
        grid-template-columns: 1fr 1fr;
      }
    }

    /* process steps */
    .steps {
      display: flex;
      justify-content: space-between;
      position: relative;
    }

    .steps::before {
      content: '';
      position: absolute;
      top: 28px;
      left: 8%;
      right: 8%;
      height: 1px;
      background: repeating-linear-gradient(to right, var(--border) 0px, var(--border) 6px, transparent 6px, transparent 12px);
      z-index: 0;
    }

    .step {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 12px;
      z-index: 1;
      flex: 1;
    }

    .step-circle {
      width: 56px;
      height: 56px;
      border-radius: 50%;
      background: var(--surface);
      border: 2px solid var(--primary);
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 700;
      font-size: 18px;
      color: var(--primary-dark);
      transition: all var(--transition);
    }

    .step:hover .step-circle {
      background: var(--primary);
      color: white;
    }

    .step h4 {
      font-size: 16px;
      font-weight: 600;
    }

    .step p {
      font-size: 14px;
      color: var(--text-secondary);
      text-align: center;
    }

    @media (max-width: 767px) {
      .steps {
        flex-direction: column;
        gap: 28px;
        align-items: flex-start;
      }
      .steps::before {
        display: none;
      }
      .step {
        flex-direction: row;
        gap: 16px;
        align-items: center;
      }
    }

    /* cases */
    .logo-wall {
      display: flex;
      flex-wrap: wrap;
      gap: 32px;
      justify-content: center;
      margin-bottom: 48px;
    }

    .logo-placeholder {
      width: 100px;
      height: 48px;
      background: #e9ecef;
      border-radius: 8px;
      filter: grayscale(1);
      opacity: 0.7;
      transition: all var(--transition);
    }

    .logo-placeholder:hover {
      filter: grayscale(0);
      opacity: 1;
    }

    .case-cards {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 24px;
    }

    .case-card {
      background: var(--surface);
      border-radius: var(--radius);
      overflow: hidden;
      box-shadow: var(--shadow-card);
      transition: all var(--transition);
    }

    .case-card:hover {
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
    }

    .case-img {
      aspect-ratio: 16/9;
      background: #f0f2f5;
    }

    .case-img img {
      width: 100%;
      height: 100%;
      object-fit: cover;
    }

    .case-body {
      padding: 20px;
    }

    .case-body h3 {
      font-size: 18px;
      font-weight: 600;
    }

    .case-body p {
      font-size: 14px;
      color: var(--text-secondary);
      margin: 8px 0;
    }

    .tag {
      display: inline-block;
      background: var(--primary-light);
      color: var(--primary-dark);
      font-size: 12px;
      padding: 4px 12px;
      border-radius: 20px;
    }

    @media (max-width: 767px) {
      .case-cards {
        grid-template-columns: 1fr;
      }
    }

    /* faq */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }

    .faq-item {
      background: var(--surface);
      border-radius: var(--radius);
      margin-bottom: 12px;
      box-shadow: var(--shadow-card);
      overflow: hidden;
    }

    .faq-question {
      padding: 20px 24px;
      font-weight: 600;
      font-size: 18px;
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      border-left: 3px solid transparent;
      transition: all var(--transition);
    }

    .faq-item.open .faq-question {
      border-left: 3px solid var(--primary);
    }

    .faq-icon {
      font-size: 20px;
      transition: transform 0.3s;
    }

    .faq-item.open .faq-icon {
      transform: rotate(45deg);
    }

    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      background: #F9FAFB;
    }

    .faq-item.open .faq-answer {
      max-height: 200px;
    }

    .faq-answer p {
      padding: 16px 24px;
      color: var(--text-secondary);
    }

    /* cta banner */
    .cta-banner {
      background: linear-gradient(135deg, #2A2A2A 0%, #3D352A 100%);
      color: white;
      text-align: center;
      padding: 80px 0;
    }

    .cta-banner h2 {
      font-size: 32px;
      color: white;
      margin-bottom: 12px;
    }

    .cta-banner p {
      color: rgba(255,255,255,0.75);
      margin-bottom: 32px;
    }

    /* footer */
    .site-footer {
      background: #1F2329;
      color: #B0B8C1;
      padding: 60px 0 30px;
    }

    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
    }

    .footer-brand p {
      margin-top: 12px;
      font-size: 14px;
    }

    .footer-col h4 {
      color: white;
      font-weight: 600;
      margin-bottom: 16px;
    }

    .footer-col a {
      display: block;
      font-size: 14px;
      margin-bottom: 8px;
      color: #B0B8C1;
    }

    .footer-col a:hover {
      color: var(--primary);
    }

    .copyright {
      border-top: 1px solid rgba(255,255,255,0.08);
      margin-top: 40px;
      padding-top: 20px;
      font-size: 13px;
      text-align: center;
    }

    @media (max-width: 767px) {
      .footer-grid {
        grid-template-columns: 1fr;
      }
    }