JSFiddle - React, Tailwind, and code Playground

HTML

<script>
    function changeBg(color) {
 	var color = '#' + color;
    document.body.style.background = color;
}
</script>
<button onclick="changeBg('ffc300')">Yellow Background</button>
<button onclick="changeBg('00ff12')">Blue Background</button>
<button onclick="changeBg('1800ff')">Green Background</button>

CSS

body {
 background-color:#111111;   
}