style.css

body {
    margin: 0;
    font-family: sans-serif;
    background-color: #0f0f0f;
    color: #f0f0f0;
}

section {
    margin: auto;
    padding: 0.75rem 1rem 1rem;
    max-width: 35rem;
    text-align: center;
}

img {
    display: block;
    width: 100%;
}

a {
    text-decoration: none;
    color: #f0f0f0;
}

nav {
    display: flex;
    position: absolute;
    left: 0;
}

nav a {
    display: block;
    padding: 1rem;
}

#canvas {
    display: block;
    width: 100%;
    height: 100vh;
    /* cursor: pointer; */
}

.controlButton {
    position: absolute;
    width: 2.5rem;
    padding: 0;
    right: 0;
    top: 100vh;
    transform: translate(-50%, -150%);
    background-color: rgba(0, 0, 0, 0.2);
    border: none;
    border-radius: 0.3rem;
}

.controlButton:hover {
    background-color: rgba(0, 0, 0, 0.5);
}

/* Why not? */
@media not all and (pointer: fine) {
    html {
        font-size: 3em;
    }
}

@media (max-width: 48rem) {
    nav {
        position: static;
    }

    h1 {
        margin-top: 0;
    }
}