Check your cache and/or cookies is the first thing. It happens from time to time. I think in almost every instance of that bug, people just had to clear out their cache (the browser maybe stuck in a loop loading on the most recent CSS settings for formatting or something) or reset/flush your cookies (maybe something go locked?).

It's usually a browser thing. Did you try any other browsers first?

First, flush out your cache (keep your cookies for now).

If that doesn't work, try another broswer (assuming you have an alt installed or willing to install one.) Or just skip to the next step.

That don't work, try resetting your cookies. I save this for last because resetting settings on a bunch of your favorite websites sucks. A lot. So I'd do this as a last resort.

The highlight works for me right now, so it's probably your browser.