    <style>
        /* Theme Variables */
        :root {
            /* Light Theme (Default) */
            --primary-color: #0f172a;
            --accent-color: #2563eb;
            --accent-hover: #1d4ed8;
            --text-color: #334155;
            --text-muted: #64748b;
            --bg-color: #f8fafc;
            --card-bg: #ffffff;
            --border-color: #e2e8f0;
            --toggle-bg: #e2e8f0;
            --toggle-text: #0f172a;
        }

        [data-theme="dark"] {
            /* Dark Theme */
            --primary-color: #f8fafc;
            --accent-color: #3b82f6;
            --accent-hover: #60a5fa;
            --text-color: #cbd5e1;
            --text-muted: #94a3b8;
            --bg-color: #0f172a;
            --card-bg: #1e293b;
            --border-color: #334155;
            --toggle-bg: #334155;
            --toggle-text: #f8fafc;
        }

        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
            transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease;
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
            background-color: var(--bg-color);
            color: var(--text-color);
            line-height: 1.6;
            padding: 0;
        }

        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 40px 20px;
            position: relative;
        }

        /* Top Bar with Theme Button */
        .top-bar {
            display: flex;
            justify-content: flex-end;
            margin-bottom: 20px;
        }

        .theme-toggle {
            background-color: var(--toggle-bg);
            color: var(--toggle-text);
            border: none;
            padding: 8px 16px;
            border-radius: 20px;
            cursor: pointer;
            font-weight: 600;
            font-size: 0.85rem;
            display: flex;
            align-items: center;
            gap: 8px;
            box-shadow: 0 1px 3px rgba(0,0,0,0.1);
        }

        .theme-toggle:hover {
            opacity: 0.9;
        }

        /* Header & Intro Section */
        header {
            text-align: center;
            margin-bottom: 50px;
            padding-bottom: 30px;
            border-bottom: 1px solid var(--border-color);
        }

        h1 {
            color: var(--primary-color);
            font-size: 2.5rem;
            margin-bottom: 15px;
            font-weight: 700;
        }

        .intro-text {
            font-size: 1.15rem;
            color: var(--text-muted);
            max-width: 800px;
            margin: 0 auto;
        }

        /* Tile Grid */
        .grid-container {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 25px;
        }

        .tile {
            background-color: var(--card-bg);
            border: 1px solid var(--border-color);
            border-radius: 12px;
            padding: 30px;
            text-decoration: none;
            color: inherit;
            display: flex;
            flex-direction: column;
            justify-content: space-between;
        }

        /* Hover effects */
        .tile:hover {
            transform: translateY(-4px);
            box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
            border-color: var(--accent-color);
        }
        
        .tile { transition: transform 0.2s ease, box-shadow 0.2s ease, background-color 0.3s ease, border-color 0.3s ease; }

        .tile-content h2 {
            color: var(--primary-color);
            font-size: 1.35rem;
            margin-bottom: 10px;
        }

        .tile-content p {
            color: var(--text-muted);
            font-size: 0.95rem;
            margin-bottom: 20px;
        }

        .tile-link {
            color: var(--accent-color);
            font-weight: 600;
            font-size: 0.95rem;
            display: flex;
            align-items: center;
        }

        .tile:hover .tile-link {
            color: var(--accent-hover);
        }

        /* Footer */
        footer {
            text-align: center;
            margin-top: 60px;
            padding-top: 20px;
            border-top: 1px solid var(--border-color);
            font-size: 0.85rem;
            color: var(--text-muted);
        }

        /* Responsive adjustments */
        @media (max-width: 600px) {
            h1 { font-size: 2rem; }
            .intro-text { font-size: 1rem; }
            .grid-container { grid-template-columns: 1fr; }
        }
    </style>