@Sieghelm_Lockayer: @Kemonophonic:
For the last several days, using the site on desktop when not logged in, every time I visit a page on Twitter I get an annoying "Log in or Register" popup covering the page that I have to click the X on to dismiss. Every. Page. And worse, if I try to click on clickable from a Twitter page to go to another one (including clicking an image to see it embiggened), it pops up that nagging "Log in or Register" thing again, but this time clicking the X to dismiss it also makes the page go back, so it won't let me see the thing I tried to click on, no matter what it is. The only way around that is to open links in a new tab (for links that can be opened in a new tab, at least); that page will still get the nagging popup, but clicking the X to dismiss it leaves me on the page that way.

@Watsit: That's really weird, because I'm not having any of the problems you are talking about and I made sure I'm logged out and tested on Chrome and Opera. The only thing even remotely similar is a tiny "warning" below saying that Twitter is better on the app, I just dismiss it and it doesn't bother me anymore. Maybe it's a regional thing? Or the update that makes that somehow hadn't arrived for me? Well... lucky me, I guess.