* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: system-ui, -apple-system, sans-serif;
    background: #f4f4f6;
    color: #222;
    min-height: 100vh;
}

header {
    background: #2563eb;
    color: #fff;
    padding: 1.5rem;
    text-align: center;
}

main {
    max-width: 640px;
    margin: 2rem auto;
    padding: 0 1rem;
    text-align: center;
}

button {
    background: #2563eb;
    color: #fff;
    border: none;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    border-radius: 8px;
    cursor: pointer;
}

button:hover {
    background: #1d4ed8;
}

.oculto {
    display: none;
}

#saludo {
    margin-top: 1rem;
    font-size: 1.2rem;
}