body {
    padding: 0;
    margin: 0;
    background: black;
    font-family: sans-serif;
}

@keyframes rotating {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(-360deg);
    }
}

.throbber {
    display: inline-block;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    padding: 0;
    margin: 0 0 0 0.5em;
    vertical-align: -50%;
    animation: rotating 2s linear infinite;
}

#canvas {
    position: absolute;
}

#overlay {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 20em;
    transform: translate(-50%, -50%);
}

#overlay .text {
    padding: 0.5em;
    margin: 0.25em;
    background: #eeeeffee;
    text-align: center;
    border: solid 1px darkgray;
    border-radius: 4px;

    display: none;
}

#overlay .text h1 {
    font-size: large;
}

#overlay .text td {
    text-align: left;
    padding: 0.1em 0.5em;
}

#nav {
    position: absolute;
    right: 0;
    height: 100%;
}

#help {
    background: white;
    width: 1.25em;
    height: 1.25em;
    margin: 0.25em;
    border: solid 1px black;
    border-radius: 2px;
    user-select: none;
}

#help:hover {
    background: cyan;
}

#help:active {
    background: darkblue;
}

#help div {
    position: relative;
    top: 50%;
    left: 50%;
    text-align: center;
    transform: translate(-50%, -50%);
}

#helpText kbd {
    display: inline-block;
    padding: 0.1em;
    min-width: 1em;
    border: solid 1px black;
    border-radius: 2px;
}