<!DOCTYPE html>
<html>
<head>
<style>
#t:before { content: "a" }
</style>
</head>
<body>
<span id="t">
<span style="display: table-cell">b</span><script>document.body.offsetWidth</script><span style="display: table-cell">c</span>
d
</span>
</body>
</html>