I've been having a problem too. Looks like there was a recent update, but the CSS or whatever formatting tool was not installed correctly so the site isn't rendering correctly (see attached picture for what the site looks like for me presently). I can log in, but I cannot get the daily check-in popup to work, nor can I get to any of the activity pages to render either.
I've tried accessing the site from my phone, a tablet and 2 different laptops, and a desktop - from 3 different US states (ISPs) - so, no, it's not just a browser issue.
I recalled this happened once before a few years back and I had to wait for the next update of whatever broke before it fixed itself. I don't know if it's the site itself that's broken or something that broke where the site is being hosted. The site was working for me 10/23, but then I didn't try logging in again until 10/27. By 10/27 I was having this issue so I assume the update was made somewhere between those dates.
My plan was to just wait it out like last time and hope it fixed itself sooner than later.
FYI - something must have updated last night and it's broken again. Site was fine yesterday, but this morning it looks like my screen print above again. Unable to check in or access any offers/surveys.
It's working again this morning. I tried latest version of Firefox, Chrome, and IE (version prior to Edge). On a Windows 7 OS, on 2 different computers. Also Chrome on an Android tablet. All had the same issue. Whatever it is, it doesn't seem to be platform or browser dependent. It had been a while since this occurred. Hopefully whatever it is has stabilized again and won't see it for another several years. Wonder if the issue is with the hosting site not upgrading something?
To me it looks like the style sheets being used on the website were not installed properly to render the site. If your site is compiled and uses dll files, it could be the hosting site didn't deploy them properly which could result in that outcome. Or if the hosting server didn't do an upgrade properly which may impact how style sheets render a site. Just guessing based on my experience with such code/deployment troubleshooting.