well what size photos do you allow? This will throw off even the best intentions of html
How can a page constrain to 760 pixel width when all the information sums more than the width.
This is going to very by install and you need to see what the deal is. What is your thumbnail size set to?
Remember if you have 5 thumbs on your prev/next bar and thumbs are set to 150 pixels how is the page going to stay within 780pixels?