<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
<style>
.gradient {
height: 250px;
width: 250px;
background-color: blue;
background-image: radial-gradient(at 0% 30%, #ff0509 10px, #fff700 30%, #05ff33 50%);
}
</style>
</head>
<body>
<div class="gradient"></div>
</body>
</html>