<!DOCTYPE html>
<html lang="en">
<head>
<style>
#back {
width: 1000px;
height: 600px;
background-color: green;
}
#front {
width: 800px;
height: 400px;
background-color: red;
border: 50px solid blue;
padding: 50px;
-webkit-mask-image: url(resources/circle.png);
-webkit-mask-size: 50px;
-webkit-mask-repeat: round;
-webkit-mask-origin: content-box;
-webkit-mask-clip: content-box;
</style>
</head>
<body>
<div id="back">
<div id="front" />
</div>
</body>
</html>
