Try looking just above the opening <form> tag in the page source. You should see something like <div id="wpcf7-f3043-p1019-o1" class="wpcf7">. See the id? You should be able to use that to target CSS at a specific form.
If that comes across as rude, I don't mean it too.
Not at all. I just didn't think you should jump through hoops to replicate something that's already generated by the plugin. :-)