How do I set a "Pressed" State?

How do I setup a “Pressed” state. I know hover is a default option. But I want to be able to dynamically change the css of an element when the mouse button is being clicked. This seems like a pretty common functionality, so I assume I am just missing something. I know we can setup custom states, but I am not sure what condition I would set for this.

This would also need to supersede the hover state. Is there a way to set “priority” for states if multiple conditions are simultaneously met?