Think of Boxes (AKA the box model) within Boxes
Body: the outer box.
is where I do most of the
Overall (default) stuff for the file like base font, base Screen margin, linespace (if needed)
P: set the indent, Justification, Paragraph Margin (Top/Bottom)
Now think of doing everything else as an EXCEPTION (overrides the base)
.classes : for titles, special dialogs...
What you end up with is a K.I.S.S. CSS