Add CSS relative to specific elements

The ability to add CSS to specific elements (submit button on form for instance) and have it automatically added to the ‘stylesheet’ page would be a real bonus! Alternatively, the ability to add a unique identifier on any element on a page would allow us with technical knowledge to send styles to that specific element (such as rounding the corners on a submit button via css for browsers that have the capability - which now that I think of it should be a checkbox option on the submit button for those that don’t want to use images)