Sure you can format form elements. Just apply the style to the various form input elements as you would any other tags. You can do such things as hide their borders, change their background colors, change their fonts etc.
Below I have put a style on the form tag to change its border and added some padding to the left.
border: 1px solid #c0c0c0;
You can also modify the input elements. Below I make all the fields of my form have a red background...
The above code would make my radio buttons, checkboxes, textboxes etc with a red background. Of course this won't effect things like textareas or select drop down boxes. But you can modify those tags as well.