/* roulang page: index */
:root {
      --primary: #1A1D24;
      --accent: #D4AF37;
      --bg: #FAFAF8;
      --card-bg: #FFFFFF;
      --border: #E8E6E1;
      --text-primary: #1A1D24;
      --text-secondary: #6B6D72;
      --success: #2E7D32;
      --radius: 8px;
      --shadow-sm: 0 1px 3px rgba(0,0,0,0.04), 0 1px 2px rgba(0,0,0,0.06);
      --shadow-hover: 0 4px 12px rgba(0,0,0,0.08), 0 2px 4px rgba(0,0,0,0.04);
      --font-sans: 'Inter', -apple-system, "PingFang SC", "Microsoft YaHei", "Noto Sans SC", sans-serif;
      --transition: 0.25s ease;
      --section-gap: 120px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    html {
      scroll-behavior: smooth;
      -webkit-font-smoothing: antialiased;
    }
    body {
      font-family: var(--font-sans);
      background-color: var(--bg);
      color: var(--text-primary);
      line-height: 1.7;
      font-size: 16px;
      overflow-x: hidden;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: var(--transition);
    }
    button {
      font-family: inherit;
      cursor: pointer;
      border: none;
      background: none;
    }
    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 40px;
    }
    @media (max-width: 1024px) {
      .container {
        padding: 0 24px;
      }
      :root {
        --section-gap: 80px;
      }
    }
    @media (max-width: 768px) {
      .container {
        padding: 0 16px;
      }
      :root {
        --section-gap: 64px;
      }
    }

    /* header / nav */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 100;
      transition: background 0.3s ease, backdrop-filter 0.3s ease;
      background: rgba(250,250,248,0.92);
      backdrop-filter: blur(12px);
      border-bottom: 1px solid transparent;
    }
    .header.scrolled {
      border-bottom: 1px solid var(--border);
    }
    .nav {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 72px;
    }
    .logo {
      display: flex;
      align-items: center;
      gap: 8px;
      font-weight: 700;
      font-size: 20px;
      color: var(--primary);
      letter-spacing: -0.01em;
      white-space: nowrap;
    }
    .logo-icon {
      width: 10px;
      height: 10px;
      background: var(--accent);
      transform: rotate(45deg);
      border-radius: 1px;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
    }
    .nav-links a {
      font-weight: 500;
      font-size: 15px;
      color: var(--text-secondary);
      transition: color 0.2s;
      position: relative;
    }
    .nav-links a:hover,
    .nav-links a.active {
      color: var(--primary);
    }
    .nav-actions {
      display: flex;
      align-items: center;
      gap: 16px;
    }
    .search-icon {
      background: none;
      border: none;
      cursor: pointer;
      padding: 4px;
      display: flex;
      align-items: center;
    }
    .search-icon svg {
      stroke: var(--text-secondary);
      transition: stroke 0.2s;
    }
    .search-icon:hover svg {
      stroke: var(--primary);
    }
    .login-link {
      font-weight: 500;
      font-size: 15px;
      color: var(--text-secondary);
    }
    .login-link:hover {
      color: var(--primary);
    }
    .btn-primary {
      background: var(--accent);
      color: var(--primary);
      font-weight: 600;
      font-size: 15px;
      padding: 10px 24px;
      border-radius: var(--radius);
      transition: background 0.2s, transform 0.15s;
      display: inline-block;
      border: none;
      cursor: pointer;
      white-space: nowrap;
    }
    .btn-primary:hover {
      background: #C19B2E;
      transform: translateY(-1px);
      box-shadow: 0 4px 10px rgba(212,175,55,0.3);
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      background: none;
      border: none;
      cursor: pointer;
      padding: 4px;
    }
    .hamburger span {
      display: block;
      width: 24px;
      height: 2px;
      background: var(--primary);
      transition: 0.2s;
    }
    @media (max-width: 1024px) {
      .nav-links, .nav-actions .search-icon, .nav-actions .login-link {
        display: none;
      }
      .hamburger {
        display: flex;
      }
      .mobile-menu {
        position: fixed;
        top: 72px;
        left: 0;
        width: 100%;
        background: var(--bg);
        flex-direction: column;
        padding: 24px 24px;
        gap: 20px;
        border-bottom: 1px solid var(--border);
        display: none;
        z-index: 99;
      }
      .mobile-menu.active {
        display: flex;
      }
      .mobile-menu a {
        font-size: 18px;
        font-weight: 500;
        color: var(--primary);
      }
      .mobile-menu .btn-primary {
        align-self: flex-start;
      }
    }

    /* sections general */
    section {
      padding: var(--section-gap) 0;
    }
    .section-title {
      font-weight: 600;
      font-size: 40px;
      line-height: 1.2;
      letter-spacing: -0.01em;
      margin-bottom: 16px;
      color: var(--primary);
    }
    .section-sub {
      font-size: 18px;
      color: var(--text-secondary);
      max-width: 600px;
      margin-bottom: 48px;
    }
    @media (max-width: 768px) {
      .section-title {
        font-size: 32px;
      }
      .section-sub {
        font-size: 16px;
      }
    }
    @media (max-width: 480px) {
      .section-title {
        font-size: 28px;
      }
    }

    /* hero */
    .hero {
      min-height: 100vh;
      display: flex;
      align-items: center;
      padding-top: 80px;
    }
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 60px;
      align-items: center;
    }
    .hero-tag {
      display: flex;
      align-items: center;
      gap: 12px;
      font-weight: 500;
      font-size: 13px;
      letter-spacing: 0.08em;
      color: var(--text-secondary);
      text-transform: uppercase;
      margin-bottom: 24px;
    }
    .hero-tag::before {
      content: '';
      width: 24px;
      height: 2px;
      background: var(--accent);
    }
    h1 {
      font-weight: 700;
      font-size: 56px;
      line-height: 1.15;
      letter-spacing: -0.02em;
      color: var(--primary);
      margin-bottom: 24px;
    }
    .hero-desc {
      font-size: 18px;
      line-height: 1.6;
      color: var(--text-secondary);
      max-width: 480px;
      margin-bottom: 40px;
    }
    .hero-actions {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--primary);
      color: var(--primary);
      font-weight: 600;
      font-size: 15px;
      padding: 14px 32px;
      border-radius: var(--radius);
      transition: 0.2s;
      display: inline-block;
    }
    .btn-outline:hover {
      background: var(--primary);
      color: var(--bg);
    }
    .hero-image {
      position: relative;
      border-radius: var(--radius);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
    }
    .hero-image img {
      width: 100%;
      height: auto;
      object-fit: cover;
      aspect-ratio: 4/3;
      border-radius: var(--radius);
    }
    .hero-badge {
      position: absolute;
      bottom: 20px;
      right: 20px;
      background: white;
      padding: 16px 20px;
      border-radius: var(--radius);
      box-shadow: var(--shadow-sm);
      font-weight: 500;
      font-size: 14px;
      color: var(--primary);
      display: flex;
      flex-direction: column;
      gap: 4px;
    }
    .hero-badge strong {
      font-size: 20px;
      color: var(--success);
    }
    @media (max-width: 1024px) {
      .hero-grid {
        grid-template-columns: 1fr;
        gap: 40px;
      }
      h1 {
        font-size: 42px;
      }
    }
    @media (max-width: 480px) {
      h1 {
        font-size: 32px;
      }
      .hero-desc {
        font-size: 16px;
      }
    }

    /* value props */
    .value-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .value-card {
      background: var(--card-bg);
      border: 1px solid var(--border);
      border-radius: var(--radius);
      padding: 32px;
      transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    }
    .value-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
      border-color: var(--primary);
    }
    .value-icon {
      width: 40px;
      height: 40px;
      color: var(--accent);
      margin-bottom: 24px;
    }
    .value-card h3 {
      font-weight: 600;
      font-size: 20px;
      margin-bottom: 12px;
    }
    .value-card p {
      color: var(--text-secondary);
      font-size: 15px;
      line-height: 1.6;
    }
    @media (max-width: 768px) {
      .value-grid {
        grid-template-columns: 1fr;
      }
    }

    /* features with tabs */
    .features-layout {
      display: grid;
      grid-template-columns: 250px 1fr;
      gap: 48px;
    }
    .feature-tabs {
      display: flex;
      flex-direction: column;
      gap: 8px;
    }
    .feature-tab {
      padding: 14px 16px;
      font-weight: 500;
      font-size: 16px;
      color: var(--text-secondary);
      border-left: 3px solid transparent;
      cursor: pointer;
      transition: 0.2s;
      background: transparent;
    }
    .feature-tab.active {
      color: var(--primary);
      font-weight: 600;
      border-left-color: var(--accent);
    }
    .feature-content {
      display: none;
      animation: fadeIn 0.4s ease;
    }
    .feature-content.active {
      display: block;
    }
    .feature-content img {
      border-radius: var(--radius);
      margin-top: 24px;
      width: 100%;
      aspect-ratio: 16/9;
      object-fit: cover;
    }
    @media (max-width: 768px) {
      .features-layout {
        grid-template-columns: 1fr;
      }
      .feature-tabs {
        flex-direction: row;
        overflow-x: auto;
        gap: 16px;
        padding-bottom: 8px;
      }
      .feature-tab {
        border-left: none;
        border-bottom: 3px solid transparent;
        white-space: nowrap;
      }
      .feature-tab.active {
        border-bottom-color: var(--accent);
      }
    }

    /* scenarios */
    .scenario-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 24px;
    }
    .scenario-card {
      background: var(--card-bg);
      border: 1px solid var(--border);
      border-radius: var(--radius);
      overflow: hidden;
      transition: 0.3s;
    }
    .scenario-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
    }
    .scenario-card img {
      width: 100%;
      height: 200px;
      object-fit: cover;
    }
    .scenario-text {
      padding: 24px;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    .scenario-text h3 {
      font-weight: 600;
      font-size: 20px;
      margin-bottom: 8px;
    }
    .arrow-link {
      font-size: 20px;
      transition: transform 0.2s;
    }
    .scenario-card:hover .arrow-link {
      transform: translateX(6px);
    }
    @media (max-width: 768px) {
      .scenario-grid {
        grid-template-columns: 1fr;
      }
    }

    /* cases */
    .cases-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 32px;
    }
    .case-item {
      display: flex;
      gap: 24px;
      align-items: center;
      padding-bottom: 32px;
      border-bottom: 1px solid var(--border);
    }
    .case-number {
      font-weight: 700;
      font-size: 48px;
      color: var(--success);
      line-height: 1;
    }
    .case-text a {
      color: var(--primary);
      font-weight: 500;
      text-decoration: underline 1px solid var(--accent);
      text-underline-offset: 4px;
    }
    @media (max-width: 768px) {
      .cases-grid {
        grid-template-columns: 1fr;
      }
      .case-item {
        flex-direction: column;
        align-items: flex-start;
      }
    }

    /* pricing */
    .pricing-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .pricing-card {
      background: var(--card-bg);
      border: 1px solid var(--border);
      border-radius: var(--radius);
      padding: 32px;
      text-align: center;
      transition: 0.2s;
    }
    .pricing-card.featured {
      border: 2px solid var(--accent);
      position: relative;
    }
    .badge {
      background: var(--accent);
      color: var(--primary);
      font-weight: 600;
      font-size: 12px;
      padding: 4px 12px;
      border-radius: 4px;
      display: inline-block;
      margin-bottom: 16px;
    }
    .price {
      font-weight: 700;
      font-size: 48px;
      color: var(--primary);
      margin: 16px 0;
    }
    .price span {
      font-size: 16px;
      font-weight: 400;
    }
    .feature-list {
      list-style: none;
      text-align: left;
      margin: 24px 0;
      color: var(--text-secondary);
    }
    .feature-list li::before {
      content: "✓";
      color: var(--accent);
      margin-right: 8px;
    }
    @media (max-width: 1024px) {
      .pricing-grid {
        grid-template-columns: 1fr;
        max-width: 400px;
        margin: 0 auto;
      }
    }

    /* faq */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }
    .faq-item {
      border-bottom: 1px solid var(--border);
    }
    .faq-question {
      width: 100%;
      text-align: left;
      font-weight: 600;
      font-size: 16px;
      padding: 20px 0;
      display: flex;
      justify-content: space-between;
      align-items: center;
      background: transparent;
      border: none;
      cursor: pointer;
    }
    .faq-icon {
      font-size: 20px;
      color: var(--accent);
      transition: transform 0.25s;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      color: var(--text-secondary);
      font-size: 15px;
      line-height: 1.7;
      padding: 0 0;
    }
    .faq-item.open .faq-answer {
      max-height: 200px;
      padding-bottom: 16px;
    }
    .faq-item.open .faq-icon {
      transform: rotate(45deg);
    }

    /* cta banner */
    .cta-banner {
      background: var(--primary);
      color: var(--bg);
      padding: 100px 0;
      text-align: center;
    }
    .cta-banner h2 {
      color: white;
    }

    /* footer */
    .footer {
      background: var(--primary);
      color: #A0A2A6;
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
    }
    .footer a:hover {
      color: var(--accent);
    }
    .copyright {
      text-align: center;
      padding-top: 40px;
      font-size: 13px;
      border-top: 1px solid #2a2d33;
      margin-top: 40px;
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }
    @keyframes fadeIn {
      from { opacity: 0; transform: translateY(10px); }
      to { opacity: 1; transform: translateY(0); }
    }