<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
*{
margin: 0;
padding: 0;
list-style: none;
}
body{
background: black;
}
#div1{
width: 500px;
height: 500px;
margin: 100px auto;
border: 1px solid transparent;
}
#div2{
width: 400px;
height: 400px;
border: 1px solid transparent;
background-color: green;
margin: 50px;
}
#div3{
width: 300px;
height: 300px;
margin: 50px;
background-color: gold;
border: 1px solid transparent;
}
#div4{
width: 200px;
height: 200px;
margin: 50px;
background-color: black;
border: 1px solid transparent;
}
#div5{
width: 100px;
height: 100px;
margin: 50px;
background-color: palevioletred;
}
</style>
</head>
<body>
<div id="div1" style="background-color: red;">
<div id="div2">
<div id="div3">
<div id="div4">
<div id="div5"></div>
</div>
</div>
</div>
</div>
</body>
<script>
window.onload=function(){
window.setInterval(function(){
document.getElementById("div1").style.backgroundColor="rgb("+Math.random()*255+","+ Math.random()*255+","+ Math.random()*255+")";
document.getElementById("div2").style.backgroundColor="rgb("+Math.random()*255+","+ Math.random()*255+","+ Math.random()*255+")";
document.getElementById("div3").style.backgroundColor="rgb("+Math.random()*255+","+ Math.random()*255+","+ Math.random()*255+")";
document.getElementById("div4").style.backgroundColor="rgb("+Math.random()*255+","+ Math.random()*255+","+ Math.random()*255+")";
document.getElementById("div5").style.backgroundColor="rgb("+Math.random()*255+","+ Math.random()*255+","+ Math.random()*255+")";
},1);
}
</script>
</html>
