/* roulang page: index */
:root {
      --primary-color: #1A56DB;
      --primary-hover: #1546b3;
      --secondary-color: #0D9488;
      --accent-color: #F97316;
      --dark-surface: #0F172A;
      --footer-surface: #0B1120;
      --bg-light: #F8FAFC;
      --bg-white: #FFFFFF;
      --text-main: #0F172A;
      --text-body: #334155;
      --text-muted: #64748B;
      --border-color: #E2E8F0;
      --card-radius: 14px;
      --shadow-sm: 0 4px 6px -1px rgba(15, 23, 42, 0.05);
      --shadow-md: 0 10px 25px -5px rgba(15, 23, 42, 0.06), 0 8px 10px -6px rgba(15, 23, 42, 0.04);
      --shadow-lg: 0 20px 25px -5px rgba(15, 23, 42, 0.1), 0 8px 10px -6px rgba(15, 23, 42, 0.04);
      --transition-base: all 0.28s ease-in-out;
    }

    html {
      scroll-behavior: smooth;
    }

    body {
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
      color: var(--text-body);
      background-color: var(--bg-light);
      line-height: 1.65;
      overflow-x: hidden;
      margin: 0;
      padding: 0;
    }

    h1, h2, h3, h4, h5, h6 {
      color: var(--text-main);
      font-weight: 700;
      line-height: 1.35;
    }

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

    /* Top Bar */
    .top-bar {
      background-color: var(--dark-surface);
      color: #94A3B8;
      font-size: 0.85rem;
      padding: 0.5rem 0;
      border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    }
    .top-bar a {
      color: #CBD5E1;
    }
    .top-bar a:hover {
      color: #FFFFFF;
    }

    /* Navbar */
    .navbar {
      background-color: var(--bg-white);
      box-shadow: 0 2px 10px rgba(15, 23, 42, 0.05);
      padding: 0.85rem 0;
      position: sticky;
      top: 0;
      z-index: 1020;
    }
    .brand-logo {
      display: inline-flex;
      align-items: center;
      gap: 0.65rem;
      font-weight: 800;
      font-size: 1.35rem;
      color: var(--primary-color);
      letter-spacing: -0.5px;
    }
    .brand-icon {
      width: 38px;
      height: 38px;
      border-radius: 10px;
      background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
      display: flex;
      align-items: center;
      justify-content: center;
      color: #FFFFFF;
      font-size: 1.2rem;
      box-shadow: 0 4px 10px rgba(26, 86, 219, 0.3);
    }
    .nav-link {
      font-weight: 500;
      color: var(--text-body) !important;
      padding: 0.5rem 0.85rem !important;
      border-radius: 6px;
      font-size: 0.95rem;
    }
    .nav-link:hover, .nav-link:focus {
      color: var(--primary-color) !important;
      background-color: rgba(26, 86, 219, 0.05);
    }

    /* Breadcrumb / Sub-header Bar */
    .subnav-bar {
      background-color: #EEF2F6;
      border-bottom: 1px solid var(--border-color);
      padding: 0.45rem 0;
      font-size: 0.85rem;
    }

    /* Buttons */
    .btn-brand-primary {
      background-color: var(--primary-color);
      color: #FFFFFF;
      font-weight: 600;
      border-radius: 8px;
      padding: 0.7rem 1.6rem;
      border: 1px solid var(--primary-color);
      box-shadow: 0 4px 14px rgba(26, 86, 219, 0.25);
      transition: var(--transition-base);
    }
    .btn-brand-primary:hover, .btn-brand-primary:focus {
      background-color: var(--primary-hover);
      color: #FFFFFF;
      box-shadow: 0 6px 18px rgba(26, 86, 219, 0.35);
      transform: translateY(-2px);
    }
    .btn-brand-accent {
      background-color: var(--accent-color);
      color: #FFFFFF;
      font-weight: 600;
      border-radius: 8px;
      padding: 0.7rem 1.6rem;
      border: 1px solid var(--accent-color);
      box-shadow: 0 4px 14px rgba(249, 115, 22, 0.25);
      transition: var(--transition-base);
    }
    .btn-brand-accent:hover {
      background-color: #ea580c;
      color: #FFFFFF;
      transform: translateY(-2px);
    }
    .btn-brand-outline {
      background-color: transparent;
      color: var(--primary-color);
      font-weight: 600;
      border-radius: 8px;
      padding: 0.7rem 1.6rem;
      border: 1.5px solid var(--primary-color);
      transition: var(--transition-base);
    }
    .btn-brand-outline:hover {
      background-color: var(--primary-color);
      color: #FFFFFF;
      transform: translateY(-2px);
    }

    /* Section Utilities */
    .section-block {
      padding: 5rem 0;
    }
    @media (max-width: 768px) {
      .section-block {
        padding: 3.5rem 0;
      }
    }
    .section-bg-white {
      background-color: var(--bg-white);
    }
    .section-bg-light {
      background-color: var(--bg-light);
    }
    .section-bg-dark {
      background-color: var(--dark-surface);
      color: #E2E8F0;
    }
    .section-title {
      font-size: 2.15rem;
      font-weight: 800;
      margin-bottom: 0.85rem;
      letter-spacing: -0.5px;
    }
    .section-subtitle {
      color: var(--text-muted);
      font-size: 1.05rem;
      max-width: 760px;
      margin-left: auto;
      margin-right: auto;
      margin-bottom: 3rem;
      line-height: 1.7;
    }

    /* Badges */
    .badge-soft-primary {
      background-color: rgba(26, 86, 219, 0.1);
      color: var(--primary-color);
      font-weight: 600;
      padding: 0.4rem 0.85rem;
      border-radius: 30px;
      font-size: 0.825rem;
      display: inline-flex;
      align-items: center;
      gap: 0.35rem;
    }
    .badge-soft-accent {
      background-color: rgba(249, 115, 22, 0.1);
      color: var(--accent-color);
      font-weight: 600;
      padding: 0.4rem 0.85rem;
      border-radius: 30px;
      font-size: 0.825rem;
    }
    .badge-soft-teal {
      background-color: rgba(13, 148, 136, 0.1);
      color: var(--secondary-color);
      font-weight: 600;
      padding: 0.4rem 0.85rem;
      border-radius: 30px;
      font-size: 0.825rem;
    }

    /* Modern Card Styles */
    .modern-card {
      background: var(--bg-white);
      border-radius: var(--card-radius);
      border: 1px solid var(--border-color);
      box-shadow: var(--shadow-md);
      transition: var(--transition-base);
      height: 100%;
      position: relative;
      overflow: hidden;
    }
    .modern-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-lg);
      border-color: #CBD5E1;
    }

    /* Hero Section */
    .hero-wrapper {
      position: relative;
      background: linear-gradient(180deg, #FFFFFF 0%, #F1F5F9 100%);
      padding: 4.5rem 0 5rem 0;
      border-bottom: 1px solid var(--border-color);
    }
    .hero-h1 {
      font-size: 2.85rem;
      font-weight: 800;
      line-height: 1.25;
      color: var(--text-main);
      margin-bottom: 1.25rem;
    }
    .hero-desc {
      font-size: 1.125rem;
      color: var(--text-body);
      margin-bottom: 2rem;
      line-height: 1.8;
    }
    .hero-panel-card {
      background: #FFFFFF;
      border-radius: 18px;
      border: 1px solid rgba(226, 232, 240, 0.8);
      box-shadow: 0 25px 50px -12px rgba(15, 23, 42, 0.12);
      padding: 1.5rem;
    }
    .hero-img-box {
      border-radius: 12px;
      overflow: hidden;
      max-height: 340px;
    }
    .hero-img-box img {
      width: 100%;
      height: 100%;
      object-fit: cover;
    }

    /* Icon Box */
    .icon-box {
      width: 52px;
      height: 52px;
      border-radius: 12px;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      font-size: 1.45rem;
      margin-bottom: 1.25rem;
    }

    /* Metrics */
    .metric-value {
      font-size: 2.8rem;
      font-weight: 800;
      letter-spacing: -1px;
      color: var(--primary-color);
      line-height: 1;
      margin-bottom: 0.5rem;
    }

    /* Tech Concept Line */
    .tech-step-node {
      position: relative;
      padding: 1.5rem;
      background: rgba(255, 255, 255, 0.04);
      border: 1px solid rgba(255, 255, 255, 0.12);
      border-radius: 12px;
      height: 100%;
    }
    .tech-step-number {
      font-size: 2.2rem;
      font-weight: 900;
      color: rgba(255, 255, 255, 0.15);
      line-height: 1;
      position: absolute;
      top: 1rem;
      right: 1.25rem;
    }

    /* Accordion Custom */
    .accordion-button {
      font-weight: 600;
      font-size: 1.05rem;
      color: var(--text-main);
      background-color: var(--bg-white);
      padding: 1.2rem 1.5rem;
      border: none;
    }
    .accordion-button:not(.collapsed) {
      color: var(--primary-color);
      background-color: rgba(26, 86, 219, 0.04);
      box-shadow: none;
    }
    .accordion-item {
      border: 1px solid var(--border-color);
      border-radius: 10px !important;
      margin-bottom: 0.85rem;
      overflow: hidden;
    }
    .accordion-body {
      padding: 1.25rem 1.5rem;
      color: var(--text-body);
      line-height: 1.75;
      font-size: 0.975rem;
      background: #FFFFFF;
    }

    /* Contact Form */
    .form-control, .form-select {
      border: 1.5px solid var(--border-color);
      padding: 0.75rem 1rem;
      border-radius: 8px;
      font-size: 0.95rem;
      min-height: 44px;
    }
    .form-control:focus, .form-select:focus {
      border-color: var(--primary-color);
      box-shadow: 0 0 0 3px rgba(26, 86, 219, 0.15);
    }

    /* Footer */
    .footer-dark {
      background-color: var(--footer-surface);
      color: #94A3B8;
      padding-top: 4.5rem;
      padding-bottom: 2rem;
      font-size: 0.925rem;
      border-top: 1px solid rgba(255, 255, 255, 0.08);
    }
    .footer-dark h5 {
      color: #F8FAFC;
      font-size: 1.05rem;
      font-weight: 700;
      margin-bottom: 1.35rem;
    }
    .footer-dark a {
      color: #94A3B8;
    }
    .footer-dark a:hover {
      color: #FFFFFF;
    }
    .footer-bottom {
      border-top: 1px solid rgba(255, 255, 255, 0.08);
      margin-top: 3.5rem;
      padding-top: 1.75rem;
      font-size: 0.85rem;
    }

    @media (max-width: 991px) {
      .hero-h1 {
        font-size: 2.2rem;
      }
      .metric-value {
        font-size: 2.3rem;
      }
    }