<script>
internals.settings.setCSSVariablesEnabled(true);
</script>
<style>
body {
    -webkit-var-c: green;
    -webkit-var-b: -webkit-var(c);
}
div {
    color: red;
    -webkit-var-a: -webkit-var(b);
    color: -webkit-var(a);
}
</style>
<div>
This text should be green on a white background. There should be no red visible.
</div>