<!DOCTYPE html>
<head>
<style>
div {
position: absolute;
left: 100px;
top: 100px;
width: 50vw;
height: 50vw;
background-color: black;
}
</style>
<script>
if (window.testRunner) {
addEventListener('load', function() {
// Zoom in three times. Ensure the image scales just as a div with
// an explicit vw size would.
testRunner.zoomPageIn();
testRunner.zoomPageIn();
testRunner.zoomPageIn();
});
}
</script>
</head>
<body>
<div></div>
</body>