html, body {
    margin: 0;
    padding: 0;
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
    background: #111;
    color: #eee;
}

main {
    max-width: 640px;
    margin: 4rem auto;
    padding: 0 1.5rem;
    line-height: 1.55;
}

h1 {
    font-weight: 600;
    letter-spacing: -0.01em;
    margin-bottom: 1.5rem;
}

.btn {
    appearance: none;
    border: 1px solid #444;
    background: #1d1d1d;
    color: #eee;
    padding: 0.45rem 0.9rem;
    border-radius: 6px;
    cursor: pointer;
    font: inherit;
}

.btn:hover { background: #262626; }
.btn:active { background: #2f2f2f; }