.mobile-control {
    position: absolute;
    z-index: 5;
    background-color: grey;
    opacity: 0.7;
    border-radius: 20%;
    width: 20px;
    height: 20px;
    -webkit-user-select: none;
    user-select: none;
    -webkit-touch-callout: none;
}

#canvas {
    pointer-events: none;
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    user-select: none;
}