html {
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: black;
    color: white;
    width: 100%;
    height: 100%;
}

canvas {
    max-width: 100%;
    max-height: 100%;
}

.click-catcher {
    position: absolute;
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    grid-template-rows: 1fr 1fr 1fr;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

.click-catcher > div {
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 10em;
    z-index: 1;
    background-color: dimgray;
    opacity: 0;
}

.click-catcher > div:nth-child(odd) {
    background-color: gray;
}

@media only screen and (max-device-width: 640px) {
    .click-catcher > div {
        opacity: 0.1;
    }
}