A lot of HTML class names changed in the linked commits.
Since this report was created only a few seconds before group0 synchronization finished (T340244#8987450), maybe the page content and js/css are not served from the same version of vector skin.
Hope that cached pages for logged-out viewers are not affected.
I ran into this ~10 minutes ago, after first observing the correct styling. One more page refresh, and it went back to normal. Probably not very helpful comment but I thought I'd share. This was well after group0 finished syncing.
Other fallout as a result of the recent changes noted at T319358#8989077.
Please edit or manually purge the page when you see this issue.
The HTML has changed so unfortunately this kind of issue is normal and expected - particularly on less frequented wikis - typically a week should be enough time to clear the majority of pages in the Varnish cache but clearly not all of them (T124954). We could wait a month for this kind of change but that would severely slow down development and mean poorer performance as we'd have to ship older styles for considerably longer.