JSFiddle - React, Tailwind, and code Playground

JavaScript

$(document).ready(function(){

    var colour = 1777216;
	window.setInterval(function(){
        colour = colour < 10000 ? 1000 : colour - 1000;
       $('body').css({background:ToRGBA(colour)});
	}, 50);

});

function ToRGBA(val){
   var r = (val)&0xFF;
   var g = (val>>8)&0xFF;
   var b = (val>>16)&0xFF;
   var a = (val>>24)&0xFF;   
   return "rgb(" + r + "," + g + "," + b + ")";
}