I have a potential client whose current site is using a html based form calculator. Is there an extension that i can find out there and plug-in where we can move away from the HTML? The form now allows free form text entry for height and width and performs a series of calculations to return the number of blocks of their product required. Its a little more complex than that, but that's the gist of it. Alternatively, what would be the easiest way to mix HTML with Joomla.