body {
    font-family: -apple-system, system-ui, sans-serif;
    max-width: 640px;
    margin: 4rem auto;
    padding: 0 1.5rem;
    line-height: 1.6;
    color: #222;
}
h1 { margin-bottom: 0.25rem; }
p { margin: 0.25rem 0; color: #555; }