Nikkol's way should work, Not sure theres any other way to do it. The whole premise behind CSS is that it's 'cascading' so many attributes are inherited between classes.
Heres a useful reference on CSS Structures that might help a little.
It may not sound like the most efficient way to do it, but maybe you can define a class for every major different paragraph type you want, and then apply the class to the paragraph. Doesn't look like CSS supports inheritance in an object-oriented way, like you seem to want...
If you use ASP to generate the CSS file you can expand the possibilties a little and could 'fudge' what you want probably by setting some strings up and then conditionally generate the classes with the info you want in them.