html,
body {
    overflow: hidden;
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
}

#myCanvas3d {
    position: fixed;
    left: 0px;
    top: 0px;
    width: 100%;
    height: 100%;
    display: block;
    z-index: 1;
}

#myCanvas2d {
    position: fixed;
    left: 0px;
    top: 0px;
    width: 100%;
    height: 100%;
    display: block;
    z-index: 2;
}