<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
</head>
<style>
*{
padding:0;
margin:0;
}
.box{
width:100px;
height:800px
}
.con{
width:600px;
height:500px;
margin:auto;
background:linear-gradient(to bottom,purple,blue,cyan,green,yellow,orange,red);
}
</style>
<body>
<div class="box">
<div class="con"></div>
</div>
</body>
</html>
