Since it's convenient, let me just merge my comment from the other task here.

Also table styling is funky on MediaWiki with a visible FOUC on https://www.mediawiki.org/wiki/Skin:Timeless for the infobox where it jumps from its correct position on the right to the left. (Not reproducible in Vector.)
@1997kB can only reproduce on MediaWiki wiki. I'm guessing the infobox template there doesn't have the right class (or has the wrong class).

I can now reproduce on en.wp also. Just needed cache to clear or something.

(This is affecting most tables.)

Also discussed at https://en.wikipedia.org/wiki/Wikipedia:Village_pump_(technical)#Problems_with_Tables_and_Infoboxes

Something in Timeless is adding style="width: 956px;" to <caption>...</caption>. The number 956 depends on the window width. It apparently tries to center the caption in the whole window instead of the table.

In T271473#6731938, @PrimeHunter wrote:

Also discussed at https://en.wikipedia.org/wiki/Wikipedia:Village_pump_(technical)#Problems_with_Tables_and_Infoboxes

Something in Timeless is adding style="width: 956px;" to <caption>...</caption>. The number 956 depends on the window width. It apparently tries to center the caption in the whole window instead of the table.

Yeah, always center the caption on mobile was the original request (I made) as a result of the "scroll table" solution implemented for tables wider than the container that had been live for maybe a couple weeks now. (I.e. mobile and all tables, and desktop with big tables.)

Change 655115 had a related patch set uploaded (by Isarra; owner: Isarra):
[mediawiki/skins/Timeless@master] Make giant table sticky captions css only affect giant tables

https://gerrit.wikimedia.org/r/655115

OOPS.

Yeah, that was dumb, should have tested better before deployment. Sorry, guys.

In T271473#6732450, @Isarra wrote:

Yeah, that was dumb, should have tested better before deployment. Sorry, guys.

Happens to the best of us.

Change 655115 merged by jenkins-bot:
[mediawiki/skins/Timeless@master] Make giant table sticky captions js only affect giant tables

https://gerrit.wikimedia.org/r/655115