New topic mobile CSS corruption?

Thanks for the suggestion. Yes, it persisted in safe mode.

Somehow the app had toggled out of Mobile View into Desktop View.

Selecting Mobile View was much better. (Definitely did not toggle this intentionally. Our support MediaWiki site is more accessible in Desktop mode than mobile. So I am quite aware when choosing this.)

However, the Desktop View here renders more cleanly (using the same device) on this site than ours:

It looks like our site has an extra spaces between the 3 elements in the header … which translates into line breaks that fouls everything up.