I tried to run a simple SEDE query a minute ago, while not logged in, and was of course told I had to prove I was human. Except that as you can see, I wasn't given any ability to prove it
Clicking the "I'm a Human Being" button in vain just popped up "Error: looks like you typed in the wrong words - try again".
So. I've done some web development, I know how to do some early diagnosis, see if it's something on my end; I'll pop open the browser's developer tools, and see if any files are failing to load. Unfortunately, once I opened the developer tools and refreshed the page, I saw this:
It then changed the moment I clicked anything.
I then (wisely) decided to close the developer tools, and instead bypass the Humanity check by logging in, which worked. But SEDE still seems to need a bit of fixing.
For the record: IE11, Win7, no extensions, no userscripts; AFAIK the only thing non-standard on this browser is that I leave it always zoomed in, and unzooming didn't help.