<html xmlns="
http://www.w3.org/1999/xhtml"
xmlns:xul="
http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
class="reftest-wait">
<style>
.container {
display: flex;
flex-direction: column;
outline: 1px solid black;
}
.item {
border: 0px solid pink;
box-sizing: content-box;
}
.withBorderTop {
border-top-width: 20px;
}
</style>
<script>
function doTest() {
tweakMe.classList.add('withBorderTop');
document.documentElement.removeAttribute("class");
}
window.addEventListener("MozReftestInvalidate", doTest);
</script>
<body>
<div class="container">
<xul:toolbarpaletteitem
class="item" id="tweakMe">abc</xul:toolbarpaletteitem>
<xul:toolbarpaletteitem
class="item">def</xul:toolbarpaletteitem>
<xul:toolbarpaletteitem
class="item">ghi</xul:toolbarpaletteitem>
</div>
</body>
</html>
