* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: system-ui, sans-serif;
    font-size: 14px;
}

a {
    color: #000;
    text-decoration: none;
} a:hover {
    text-decoration: underline;
}

br {
    user-select: none;
}

main {
    position: absolute;
    top: 50%; left: 50%;
    transform: translate(-50%, -50%);
    font-size: 24px;
}
footer { text-align: center; position: absolute; bottom: 4rem; width: 100%; }
iframe { min-width: 640px; min-height: 480px; width: 100%; height: 100%; }