The corners seem a bit rounded & the cat does not fill the box up completely at the sides. Setting margin: 0 could help fill up the box more. I'm not sure where the rounded corners come from, but try border-radius: 0 !important if it's unintentional.

Depending on the fit, more padding could be good.

Have you tried getting your cat involved in politics? I prefer setting left: 100% and right: 0%, but it's up to you. (Do note that these values are not inherited by children.)