<!DOCTYPE html>
<title>CSS Cascade Layers: 'revert-layer' triggers a smooth transition</title>
<link rel="help" href="https://drafts.csswg.org/css-cascade-5/#revert-layer">
<link rel="author" href="mailto:xiaochengh@chromium.org">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
@layer revert-to, revert-from;
@layer revert-from {
#target {
font-size: 10px;
transition: font-size 2s linear -1s;
}
#target.reverted {
font-size: revert-layer;
}
}
@layer revert-to {
#target { font-size: 20px; }
}
</style>
<div id="target"></div>
<script>
function raf() {
return new Promise(resolve => requestAnimationFrame(resolve));
}
promise_test(async () => {
const target = document.getElementById('target');
getComputedStyle(target).getPropertyValue('font-size');
await raf();
target.classList.toggle('reverted');
const result = getComputedStyle(target).getPropertyValue('font-size');
assert_equals(result, '15px');
}, "'revert-layer' should revert font-size to 20px and trigger a smooth transition");
</script>