/* --- General Styles & Variables --- */
        :root {
            --bg-color: #f3f4f6;
            --text-color: #1f2937;
            --card-bg: #ffffff;
            --input-bg: #f9fafb;
            --border-color: #d1d5db;
            --brand-color: #4f46e5;
            --brand-hover: #4338ca;
            --text-light: #4b5563;
            --text-lighter: #6b7280;
            --shadow-color: rgba(0, 0, 0, 0.1);
        }

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

        /* --- Layout & Components --- */
        .container { max-width: 42rem; margin: 0 auto; padding: 1rem; }
        @media (min-width: 640px) { .container { padding: 1.5rem; } }
        
        .card { background-color: var(--card-bg); border-radius: 0.5rem; box-shadow: 0 4px 6px -1px var(--shadow-color), 0 2px 4px -2px var(--shadow-color); padding: 1.5rem; }
        @media (min-width: 640px) { .card { padding: 2.5rem; } }

        /* --- Typography & Content --- */
        h1, h2, h3 { line-height: 1.2; margin-top: 0; }
        h1 { font-size: 2.25rem; font-weight: 700; color: var(--text-color); margin-bottom: 0.5rem; }
        h2 { font-size: 1.5rem; font-weight: 600; margin-top: 2.5rem; margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 1px solid var(--border-color); }
        p { margin-top: 0; margin-bottom: 1rem; }
        a { color: var(--brand-color); text-decoration: none; }
        a:hover { text-decoration: underline; color: var(--brand-hover); }
        ul, ol { padding-left: 1.5rem; margin-top: 0; margin-bottom: 1rem; }
        li { margin-bottom: 0.5rem; }
        code { background-color: #e5e7eb; padding: 0.2rem 0.4rem; border-radius: 0.25rem; font-family: monospace; }
        blockquote { margin: 1.5rem 0; padding: 0.5rem 1rem; border-left: 4px solid var(--brand-color); background-color: var(--bg-color); font-style: italic; color: var(--text-light); }

        /* --- Header & Footer --- */
        .site-header { padding: 1rem; background-color: var(--card-bg); border-bottom: 1px solid var(--border-color); margin-bottom: 2rem; }
        .site-header .container { padding-top: 0; padding-bottom: 0; display: flex; flex-direction: column; align-items: center; gap: 1rem; }
        @media (min-width: 640px) { .site-header .container { flex-direction: row; justify-content: space-between; } }
        .site-header .site-title { font-size: 1.5rem; font-weight: 700; margin: 0; }
        .site-header .site-title a { text-decoration: none; color: inherit; }
        .site-header nav ul { margin: 0; padding: 0; list-style: none; display: flex; gap: 1.5rem; }
        .site-header nav a { text-decoration: none; color: var(--text-light); font-weight: 500; transition: color 0.2s; }
        .site-header nav a:hover { color: var(--brand-color); }
        .site-footer { margin-top: 3rem; padding: 2rem 1rem; text-align: center; font-size: 0.875rem; color: var(--text-lighter); border-top: 1px solid var(--border-color); }