<!DOCTYPE html>
<title>CSS Values and Units Test: line-height transition affecting lh units</title>
<link rel="help" href="https://www.w3.org/TR/css-values-4/#lh">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
  #target {
    width: 20lh;
    line-height: 10px;
    transition: line-height 1s;
  }
  #target.lh {
    line-height: 20px;
  }
</style>
<div id="target"></div>
<script>
  let t = async_test("lh unit length should change with transitioning line-height");

  t.step(() => {
    target.offsetTop;
    target.className = "lh";
  });

  requestAnimationFrame(() => requestAnimationFrame(() => requestAnimationFrame(() => {
    t.step(() => {
      assert_not_equals(getComputedStyle(target).width, "200px");
      assert_not_equals(getComputedStyle(target).width, "400px");
      t.done();
    }, "Transition should be progressing. Not at start/end.");
  })));
</script>
