<!DOCTYPE html>
<html>
<head>
<style>
.square {
    width: 128px;
    height: 128px;
}

.blue-background {
    background-color: blue;
}

.check-credentials {
    mask-image: url("/security/resources/image-credential-check.py");
    mask-size: 128px 128px;
    -webkit-mask-image: url("/security/resources/image-credential-check.py");
    -webkit-mask-size: 128px 128px;
}
</style>
</head>
<body onload="window.testRunner.notifyDone()">
<div class="square" style="background-color: yellow">
    <div class="square blue-background check-credentials"></div>
</div>
</body>
</html>