When you choose to answer this question, why do you not specify which part of the code and what to edit? There are no clear instructions for this anywhere, yet it's such an obvious question to answer...
We support our code as it is written and do not assist in code modification.
Now if you would like a hint just as Michael said you can alter the html to suit your needs. Specifically you can create an overlay image that does not have rounded corners. Take a look in a graphics editors at the overlay images and you can create one that can suit your specific needs.