:root {
    --bg: #ffffff;
    --fg: #1f2328;
    --muted: #6e7781;
    --border: #e5e7eb;
    --surface: #f8fafc;
    --accent: #0d6efd;
    --radius: 8px;
    --container: 70ch;
}
@media (prefers-color-scheme: dark) {
    :root {
        --bg: #0d1117;
        --fg: #e6edf3;
        --muted: #9ea7b3;
        --border: #30363d;
        --surface: #161b22;
        --accent: #4aa3ff;
    }
}
*, *::before, *::after { box-sizing: border-box; }
body {
    margin: 0;
    font-family: system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, Noto Sans, Arial, sans-serif;
    line-height: 1.6;
    color: var(--fg);
    background: var(--bg);
    -webkit-font-smoothing: antialiased;
    text-rendering: optimizeLegibility;
}
.container {
    max-width: var(--container);
    margin: 0 auto;
    padding: 2rem 1rem;
}
header, footer {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
}
header .container, footer .container {
    padding-block: 1rem;
}
h1 { margin: 0 0 0.5rem; line-height: 1.2; }
p { margin: 0 0 1rem; color: var(--fg); }
.muted { color: var(--muted); }
.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1rem;
    margin-top: 1rem;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
button {
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: 6px;
    padding: 0.6rem 0.9rem;
    cursor: pointer;
}
button:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}