<!DOCTYPE>
<html>
<head>
<style>
#canvas {
width: 200px;
height: 200px;
background-color: red;
}
.blue {
width: 50px;
height: 50px;
background-color: rgba(0, 0, 255, 0.5);
top: -50px;
position: relative;
}
</style>
</head>
<body>
<div id="canvas"></div>
<div class="blue"></div>
</body>
</html>