Sure there is...
Generate custom form layout. Place a submit button on the form. Go into the source for the layout, and wrap the submit button in a div and place a class on the div, like "submit". Then you can either add a style block to the bizform source, or add to your normal css something like:
<style>
div.submit input {
background: #ccc;
border: 1px solid #222;
}
</style>