One of the errors is due to the style tag not being in the head, but unfortunately that is a side effect of being able to make the page flexible enough to work standalone or included in another php page while still only requiring a few lines of PHP for you to paste in. All of the other errors are due to the lightbox title which uses the name attribute. If you want to fix the issues, you could edit the name attributes to not include markup. PG is very much web standard in terms of its main layout and browser compatibility.
-justin