body {
margin: 0;
padding: 0;
background: #f5f5f5;
}

main {
text-align: center;
display: flex;
align-items: center;
justify-content: center;
height: 100vh;
}

canvas {
max-width: 100vw;
max-height: 90vh;
margin: auto;
overflow: auto;
position: fixed;
object-fit: contain;
}