body {
    margin: 0;
    padding: 0;
    font-family: helvetica, sans-serif;
}
canvas {
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
}
#controls {
    opacity: 0;
    margin: 10px;
    padding: 10px;
    position: absolute;
    z-index: 10;
    background-color: rgba(255,255,255,0.8);
    transition: opacity 0.3s ease;
    border-radius: 3px;
}
#controls:hover {
    opacity: 1 !important;
}
body:hover #controls {
    opacity: 0.2;
}