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

    :root {
      --app-primary: #7c3aed;
      --app-primary-dark: #6d28d9;
      --app-primary-soft: #a78bfa;
      --app-glow: rgba(124, 58, 237, 0.1);
      --bg: #fbfaff;
      --surface: #ffffff;
      --surface-card: #ffffff;
      --border: #e9e4ff;
      --text-primary: #2e1065;
      --text-secondary: #4c1d95;
      --text-muted: #6b21a5;
      --shadow-sm: 0 2px 8px rgba(0,0,0,0.02), 0 1px 2px rgba(0,0,0,0.03);
      --shadow-md: 0 12px 28px -10px rgba(0,0,0,0.05);
      --radius-card: 32px;
      --radius-element: 20px;
    }

    [data-theme="dark"] {
      --bg: #0a0c12;
      --surface: #141822;
      --surface-card: #1a1f2c;
      --border: #2d2a4a;
      --text-primary: #f1f5f9;
      --text-secondary: #cbd5e1;
      --text-muted: #94a3b8;
      --app-primary: #a78bfa;
      --app-primary-dark: #8b5cf6;
    }

    body {
      font-family: 'Inter', sans-serif;
      background: var(--bg);
      color: var(--text-primary);
      line-height: 1.5;
    }

    .wrapper {
      max-width: 1100px;
      margin: 0 auto;
      padding: 36px 24px 64px;
    }

    .back-nav {
      margin-bottom: 32px;
    }
    .back-btn {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      background: var(--surface);
      padding: 8px 20px;
      border-radius: 60px;
      font-size: 0.85rem;
      font-weight: 500;
      color: var(--text-secondary);
      text-decoration: none;
      border: 1px solid var(--border);
      transition: all 0.2s;
    }
    .back-btn:hover {
      border-color: var(--app-primary);
      color: var(--app-primary);
      transform: translateX(-3px);
    }

    /* hero - centered lock theme */
    .hero-centered {
      text-align: center;
      background: var(--surface);
      border-radius: var(--radius-card);
      padding: 36px 32px;
      margin-bottom: 56px;
      border: 1px solid var(--border);
    }
    .hero-icon img {
      width: 88px;
      height: 88px;
      border-radius: 24px;
      margin-bottom: 20px;
    }
    .hero-badge {
      display: inline-block;
      background: rgba(124, 58, 237, 0.12);
      padding: 4px 14px;
      border-radius: 30px;
      font-size: 0.7rem;
      font-weight: 600;
      color: var(--app-primary);
      margin-bottom: 16px;
    }
    .hero-title {
      font-family: 'Outfit', sans-serif;
      font-size: 2.2rem;
      font-weight: 800;
      letter-spacing: -0.02em;
      margin-bottom: 16px;
      color: var(--text-primary);
    }
    .hero-desc {
      color: var(--text-secondary);
      max-width: 650px;
      margin: 0 auto 24px;
      font-size: 1rem;
    }
    .btn-download {
      display: inline-flex;
      align-items: center;
      gap: 12px;
      background: var(--app-primary);
      color: white;
      font-weight: 600;
      padding: 12px 32px;
      border-radius: 44px;
      text-decoration: none;
      transition: 0.2s;
      box-shadow: 0 6px 14px rgba(124,58,237,0.25);
    }
    .btn-download:hover {
      background: var(--app-primary-dark);
      transform: translateY(-2px);
    }

    /* two column layout for features */
    .two-columns {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 28px;
      margin-bottom: 48px;
    }
    .feature-panel {
      background: var(--surface-card);
      border-radius: var(--radius-element);
      padding: 28px 26px;
      border: 1px solid var(--border);
    }
    .panel-title {
      font-weight: 700;
      font-size: 1.3rem;
      margin-bottom: 20px;
      display: flex;
      align-items: center;
      gap: 10px;
      color: var(--app-primary);
    }
    .feature-list {
      list-style: none;
      padding: 0;
    }
    .feature-list li {
      display: flex;
      align-items: center;
      gap: 12px;
      margin-bottom: 18px;
      font-size: 0.95rem;
      color: var(--text-secondary);
    }
    .feature-list li i {
      width: 26px;
      color: var(--app-primary);
      font-size: 1.2rem;
    }

    /* encryption highlight */
    .encryption-card {
      background: linear-gradient(135deg, var(--surface), var(--bg));
      border-radius: var(--radius-element);
      padding: 28px 32px;
      margin-bottom: 44px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      flex-wrap: wrap;
      border: 1px solid var(--border);
    }
    .encryption-text h3 {
      font-weight: 700;
      margin-bottom: 8px;
    }
    .encryption-text p {
      color: var(--text-secondary);
      font-size: 0.9rem;
    }
    .encryption-icon {
      font-size: 2.8rem;
      color: var(--app-primary);
    }

    /* use cases chips */
    .usecase-section {
      background: var(--surface-card);
      border-radius: var(--radius-element);
      padding: 28px 32px;
      margin-bottom: 44px;
      border: 1px solid var(--border);
    }
    .usecase-title {
      font-weight: 700;
      font-size: 1.2rem;
      margin-bottom: 20px;
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .chip-group {
      display: flex;
      flex-wrap: wrap;
      gap: 12px;
    }
    .chip {
      background: var(--bg);
      border: 1px solid var(--border);
      padding: 8px 22px;
      border-radius: 60px;
      font-size: 0.85rem;
      font-weight: 500;
    }
    .chip i {
      color: var(--app-primary);
      margin-right: 8px;
    }

    /* privacy card */
    .privacy-card {
      display: flex;
      justify-content: space-between;
      align-items: center;
      flex-wrap: wrap;
      background: rgba(124,58,237,0.04);
      border-radius: var(--radius-element);
      padding: 24px 28px;
      margin-bottom: 40px;
      border-left: 4px solid var(--app-primary);
    }
    .privacy-text strong {
      font-weight: 700;
    }
    .privacy-text p {
      color: var(--text-secondary);
      font-size: 0.85rem;
      margin-top: 6px;
    }
    .privacy-link {
      background: transparent;
      border: 1px solid var(--border);
      padding: 8px 24px;
      border-radius: 60px;
      text-decoration: none;
      color: var(--app-primary);
      font-weight: 500;
      transition: 0.2s;
    }
    .privacy-link:hover {
      background: var(--app-primary);
      color: white;
      border-color: var(--app-primary);
    }

    .footer {
      text-align: center;
      padding-top: 28px;
      border-top: 1px solid var(--border);
      color: var(--text-muted);
      font-size: 0.8rem;
    }
    .footer a {
      color: var(--app-primary);
      text-decoration: none;
    }

    @media (max-width: 780px) {
      .wrapper { padding: 24px 18px 48px; }
      .two-columns { grid-template-columns: 1fr; gap: 20px; }
      .encryption-card { flex-direction: column; text-align: center; gap: 16px; }
      .hero-title { font-size: 1.7rem; }
    }