web-animations/responsive/transform.html

<!DOCTYPE html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<div id='container'>
<div id='element'></div>
</div>

<script>
var element = document.getElementById('element');
var container = document.getElementById('container');

test(function() {
    container.style.fontSize = '10px';
    var player = element.animate([{transform: 'translateX(10em)'}, {transform: 'translateX(20em)'}], 10);
    player.pause();
    player.currentTime = 2;
    container.style.fontSize = '20px';
    assert_equals(getComputedStyle(element).transform, 'matrix(1, 0, 0, 1, 240, 0)');
}, 'Transform responsive to font size changes');

</script>