CSS Rendering Different in Production vs Local Development

I’m having an issue with my CSS on a dropdown button rendering differently when I deploy to production vs developing on my local machine. Does anyone have any ideas why this might be the case? I recreated the button with meteorpad: http://meteorpad.com/pad/FpXGJkBhFEJgz5nj8/Button

It seems to render correctly (the same as production) on the meteorpad example. On my local machine, the right half of the dropdown box is cut off (see photo).

This is the same whether I use Chrome, Safari, Firefox, etc on my local machine for development. The code is the exact same code running locally and in production. I’m using mup to deploy, and running on an ubuntu DO server.

PS: I seem to be dealing with this bug as well, though I think this is separate from the production rendering: css - pseudo-elements firefox problem with padding - Stack Overflow