I have posted my form from FA onto my website and it has the look and feel of my site because it references our own css. However, when the user clicks the submit button it returns a formassembly page that asks for confirmation and if any changes are needed it returns the user to the form I created on the formassebly site.
We would like it to appear that formassembly is not involved in any way.
(I know we've already answered this via email, but for the record, here's the solution:)
To keep the preview integrated with your website, you must use the "server-side script" (API) publishing option. This requires some technical knowledge so you may want to talk to your webmaster or your IT department about it.
Instructions are available here: http://app.formassembly.com/pages/support/publishing/#restapi