This was intentional per fc6ef37c9f8843ecc95aa80809141b40b18a4dee / T86003.

This needs to be reverted, after this change form elements no longer align.

Sorry to clarify, the margins portions of the patches are probably fine, but need to be broken out from the sizing changes which need to be reverted .

Indepedently, the checkbox also uses the pre-existing icon, rather than the one from mockups. Seems like there is a "tick" icon in WikiFont (or whatever the name is now), but it was discarded when we imported the icons in 06a5031fd3bf6f25f2398aff2b4999bfe224b463, as it doesn't match the mockup either (and it looked just plain ugly when I tried it right now). I'm submitting a patch for that; not touching the sizes now.

Change 200635 had a related patch set uploaded (by Bartosz Dziewoński):
MediaWiki theme: Use checkbox icon per mockups

https://gerrit.wikimedia.org/r/200635

@matmarex this task is referring to the change in the OVERALL size of the control, not the size of the graphics WITHIN the control.

Okay. In the future, I will refrain from trying to implement the parts of design changes that can be implemented immediately, if there's some detail blocking the rest.

Change 200635 merged by jenkins-bot:
MediaWiki theme: Use checkbox icon per mockups

https://gerrit.wikimedia.org/r/200635

@matmarex, not entirely sure what happened during the import. But here is the checkmark icon attached here [1] and in Dropbox where the rest of the icons are at.

Speaking of icons: T94461

[1]

Checkmark icon on Dropbox

Hey @Jdforrester-WMF, I'm reopening this, although it's a dupe because it's not yet solved.

Here's the latest: