Created attachment 297607 [details] Webkit render Here's a link to test; try to zoom out (CMD and -) https://jsfiddle.net/mven/1q5yqw4x/ `px` based padding relatively sizes down correctly, while the `em` and `rem` based ones stop scaling down at a certain point. This happens on Both Chrome and Safari, including Webkit Nightly Build. Firefox sizes all elements down correctly.