<!DOCTYPE html>
<title>transform-box: border-box (CSS layout)</title>
<link rel="match" href="./reference/cssbox-ref.html">
<link rel="help" href="https://drafts.csswg.org/css-transforms-1/#transform-box">
<meta name="assert" content="This should display a square with a black bar at the top whose top-left corner is at 100,100."/>

<style>
#target {
    width: 150px;
    height: 200px;
    margin-left: 300px;
    margin-top: 100px;
    background-color: green;
    border-left: solid 50px black;

    transform: rotate(90deg);
    transform-origin: 0 0;
    transform-box: border-box;
}
</style>

<div id="target"></div>

<div id="error"></div>
<script>
var refStyle = "border-box";
var compStyle = getComputedStyle(document.getElementById('target')).transformBox;
if (refStyle != compStyle)
    document.getElementById('error').textContent = "Error, got computed style " + compStyle;
</script>