I'm an intel Mac User running modern OS (10.10.3) using the latest Firefox (40.0) and Safari (8.0.6) to edit English Wikipedia on the secure server.
In the last few days, I've noticed a new phenomenon when my watchlist is opening or reloading. The page loads and for a fraction of a second all the page titles (all project spaces: main, talk, user, WP) are bolded, then the text reverts to plain style. Nothing except the page title bolds: not the timestamp, bit count, contributor or edit summary. I took a screen shot.
I normally use Firefox, but when I tried Apple's browser the exact same effect occurs. This does not happen when I load my contributions page. Doesn't seem to occur when I'm in MetaWiki or French Wikipedia, just en.wikipedia.org.
Don't remember changing any preferences recently, except from deleting Lupin from my .js and allowing popups from the gadget tab. Tried disabling the popups and it didn't change the effect.
This isn't a big deal and it's not affecting my work, but since it's new I though I'd mention it here right away.
Thanks for all you folks do.
Scott