device-screen {
    position: relative;
    display: block;
}

device-screen canvas {
    position: absolute;
    margin: auto;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    pointer-events: none; /* MUST HAVE */
}

device-screen .finger {
    position: absolute;
    border-radius: 50%;
    background: lime;
    opacity: 0.5;
    width: 6mm;
    height: 6mm;
    top: -3mm;
    left: -3mm;
    pointer-events: none;
    display: none;
}

device-screen.fingering .finger {
    display: block;
}

device-screen textarea {
    position: absolute;
    z-index: 10;
    outline: none;
    pointer-events: none;
    opacity: 0;
}