style.css

@font-face {
    font-family: 'monogram';
    src: url('assets/monogram-extended.ttf') format('truetype');
}
.canvas-wrapper {
    position: relative;
    width: 100%;
    height: var(--playsize, 80vmin);
    margin-bottom: 10px;
    border: 2px solid white;
}
.canvas-wrapper canvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    image-rendering: pixelated;
    image-rendering: crisp-edges;
}
.game-container {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: var(--playsize, 80vmin);
}
.input-container {
    display: inline-flex;
    width: 100%;
}
.input-container * {
    color: white;
    font-size: 1.2em;
    font-family: 'monogram';
}
.textbox-container {
    display: table-cell;
    width: 100%;
    padding-right: 0.4em;
}
.textbox-container > input {
    background: black;
    border: 2px solid;
    width: 100%;
    font-size: 0.8em;
    padding: 5px;
}
.input-container > button {
    background: none;
    border: 2px solid;
    transition: transform .2s;
    margin-right: -4px;
    margin-left: 10px;
}
.input-container > button:hover {
    transform: scale(1.05);
}
.input-container > button:active {
    transform: scale(0.9);
}
.input-error {
    border-color: red !important;
    animation: shake 0.5s;
    animation-iteration-count: 1;
}
.textbox-container > input:focus {
    box-shadow: none;
    outline: none;
}
.textbox-container > input:focus:not(.input-error) {
    animation: shrinkgrow 0.5s;
    animation-iteration-count: 1;
}
.input-container > button:focus {
    outline: none;
}
@keyframes shake {
    0%   { transform: translate( 1px, 0px); }
    10%  { transform: translate(-1px, 0px); }
    20%  { transform: translate(-3px, 0px); }
    30%  { transform: translate( 3px, 0px); }
    40%  { transform: translate( 1px, 0px); }
    50%  { transform: translate(-1px, 0px); }
    60%  { transform: translate(-3px, 0px); }
    70%  { transform: translate( 3px, 0px); }
    80%  { transform: translate(-1px, 0px); }
    90%  { transform: translate( 1px, 0px); }
    100% { transform: translate( 1px, 0px); }
}
@keyframes shrinkgrow {
    0%   { transform: scale(1); }
    50%  { transform: scale(1.05); }
    100% { transform: scale(1); }
}
body {
    color: white;
    background: black;
    overflow: hidden;
    font-family: monogram;
    font-size: 2em;
}
html, body {
    height: 100%;
}