You can’t. But you can work around it by wrapping your list in a DIV, and then using that DIV’s ID in a compound selector like #yourDiv ul. Weaver wrote an Action that allows you to add classnames to individual list items:
Sure. f-fp means First Paragraph (which gets top-margin:0) and f-lp
means Last Paragraph (which gets bottom-margin:0). Usually these get
applied to the P tags inside a DIV, so the measurements you set for
padding will work predictably. I suppose the same thing is being done
to the UL, for the same reason.
Remember you can add as many classes to an object as you like, in a
space-delimited list inside the class attribute. They apply in order,
so if you added another class later in the list that reset the
margins, it would apply without the need for !important or any other
hacks.