body, html {
    height: 100vh;
    width: 100vw;
    margin: 0px;
    background: grey;
}
.canvas {
    position:absolute;
    width:min(100vw,100vh);
}
.div {
    width: 100vw;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}
.layer0 {
    z-index:0;
}
.layer1 {
    z-index: 1;
}
.layer2 {
    z-index: 2;
}