I have investigated the issue and I have been able to replicate it neither in the current main nor by checking out main on and before May the 3rd.

I have used: Chrome, Firefox and also Browserstack version of Safari.

Below is a quick image of each button and some guidelines to show their alignment and they all align perfectly. The browserstack button seem slightly smaller, but it has the right sizes in pixel wise:

@AnneT Any chance you could try to reproduce and see if it is still a problem on your current environment

Hey @SimoneThisDot, yep, I'm still seeing this (only in a MediaWiki context, only in Firefox):

The vertical spacing is correct on the docs site.

Hei Anne, unfortunately, I do not seem to be able to help here as I cannot replicate the issue not even in the wiki environment.

I have checked my buttons and I have the correct 10 pixels on top and bottom, differently from yours, as you can see I have aligned my components to yours too to show the difference.

All this has been done on the suggested page: https://test.wikidata.org/wiki/User:Zvpunry/CodexDemo (after enabling the code)

Please let me know if have further input for me to try and help you, or we could ask Ezekiel maybe to help us replicate it. I have a windows machine and from what I can see from your screenshot you have a high density screen (your button is 64pixels).

Moving from sprint to backlog; please holler if there's a reason to bump up the priority.