Ah ha! That did the trick. Deleted the caching plugin and it fixed it. Thanks!
Nah, when this happened, it was only a dot release or two. Nothing too major. I am only posting about it now because there were workarounds to get to administer the other sites. But now that I need to add a new one, I am unable to. I just made sure all plugins and themes were up to date, and am still having the same issue. Is there any sort of cache to clear, or maybe it has something to do with permissions and/or htaccess?
Nevermind, just figured it out. Apparently, line-height was messing with it. Setting that to 0 for the div fixed it.
Oh, also, this code is in a function in functions.php. Don’t know if that matters or not.