== Bug reports == 

 I haven't come across this, so it does sound like a bug. The place to report bugs is https://bugzilla.wikimedia.org/. Based on a quick search, I didn't find anything reported that looked like what you're describing. Is it showing up on multiple browsers? Giving as much information as you can about your browser (which version, and also build number if you can figure that out) and operating system will help figure it out.