I gave this a try. It's pretty tricky, and I think you *might* be able to get it to work if you remove the text from the radio button form fields.
Note that this example uses the only fields that are radio buttons. If you could get this to work, then you could change the yes/no to a dropdown and use radio buttons for the "Meat or vegetarian?" question.
content: " ";
background: url(http://s.wordpress.org/about/images/logos/wordpress-logo-32-blue.png) 20px 0 no-repeat;
background: url(http://s.wordpress.org/about/images/logos/wordpress-logo-32.png) 20px 0 no-repeat;
There might be a better way to do this that I'm not thinking of, but it turned out to be a tougher request than I thought it would be!