CSS Class Name

The form will inherit properties from your theme CSS file if it's loaded on the same page. You can override the theme styles by using more specific rules for your form, but there's no way to simply disable the theme CSS unless you don't include it in the form page.

Example: Your theme has blue text but you want red.. you can use inheritance from the main form wrapper to force this.

.gform_wrapper {color:red}

or, if you wanted it to only apply to one specific form, use the wrapper ID rather than the class

#gform_wrapper_1 {color:red}

This might be helpful as you step through the form CSS

http://www.gravityhelp.com/documentation/visual-css-guide/