JSFiddle - React, Tailwind, and code Playground

by Aves

HTML

<canvas></canvas>

CSS

body {
    background: #779;
}
canvas {
    background: #889;
}

JavaScript

var cnv = document.getElementsByTagName('canvas')[0],
    ctx = cnv.getContext('2d');
doResize();
window.addEventListener('resize', doResize, false);

function doResize() {
    var wh = window.innerHeight,
        ww = window.innerWidth,
        cs;
    if (wh > ww) {
        cs = ww;
    } else if (ww - wh > 200) {
        cs = wh;
    } else {
        cs = ww - 200;
    }
    ctx.canvas.width = ctx.canvas.height = cs;
}