body {
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    margin: 0;
    padding: 0;
    background: #f5f5f5;
}

header {
    background: #222;
    color: #fff;
    padding: 1rem 2rem;
}

main {
    padding: 2rem;
}