Yikes. Yep, found the problem. I've put up a fix that I think should fix it. Since you didn't give much by way of details, can I get you check whatever you were doing before and see if it works now?

Hi Alex! I was unable to post or edit Details pages as well yesterday, but I figured the culprit was one of my browser add-ons. That issue, if it's related to this, is fixed!

Yep, this fix should also have fixed some problems with details pages.

Technical details: Heroku forced me to move to a new version of their Cedar stack, which meant my Rails version got updated, which meant I got strong_parameters suddenly, which broke a bunch of edit workflows. I think I've fixed everything now - editing comments, cardset options and mechanics all seem to be okay - but let me know if you think you've found any more problems.