buzztone on "[Plugin: Contact Form 7] Style form submit button"

Use Firebug or Chrome Dev Tools to see what is going on.

These tools will allow you to see which class is being used by CF7 in the wpcf7 submit button on any page. Then you can write CSS to target that class.

Alternatively you can give the submit button you want to style the class "blue_button" (not "blue button" with space) in the CF7 Form interface - you can add specific id & class to any CF7 element.