Firefox Style tab - where has it gone?

It was simple in the old Firebug but it isn't there anymore and I can't get it back? I'm sure it is simple, but where is it please?

To clarify, on the right side of the menu tabs in Firebug there was a Style tab and when you clicked it you could see the CSS changes for the :hover, :active, and :focus states.

Solution

Note that Firebug is history. What you are seeing are the Firefox DevTools.

In those tools the panel containing the CSS rules of the selected element is called Rules. And the options to toggle the :hover, :active and :focus states are available behind a button on the right side of the panel:

This and other questions are answered in the migration guide for Firebug users.