Created attachment 228078 [details] testcase - red must not be visible to pass the test When the aspect ratio of content such as an image is preserved and the height is changed via CSS animations, transitions or drag resizing, -webkit-fit-content on the parent element doesn't update to widen or narrow the width of the parent to match the new content width. In the attached testcase the red background becomes visible in the top circle with preserved aspect ratio. The bottom circle without aspect ratio kept behaves as expected. I've run the testcase in Gecko browsers and both circles behave correctly. I tested width: intrinsic instead but that also failed in webkit similarly to fit-content