index.html

<style>
    body{
        margin:0;
        background: #1a1a1a;
        /*display: flex;*/
        /*justify-content: center;*/
        /*height: 100vh;*/
        /*width: 100vw;*/
    }
    canvas {
        /*aspect-ratio: 4/3;*/
        width: 100vw;
        height: 100vh;
        object-fit: contain;
        /*margin: auto;*/
        image-rendering: pixelated;
    }
    #ruler {
        width: 66px;
        height: 100vh;
        background: lightblue;
        position: absolute;
        top:0;left:0;
        z-index: 999;
    }
</style>
<canvas id="canvas"></canvas>
<script src="./main.js"></script>
<!--<div id="ruler"></div>-->