If you like to apply multiple styles on the single element, all you have to do is separate the style names by a space. Lets say you have three classes .a {..} .b{..} .c{..} Code (markup): to apply them on a single div tag: <div class="a b c"> ..... </div> Code (markup):
I like to use multiple classes for things that I want to keep standard across the entire site. For example, if I always want the bottom-margin for elements that have a bottom-margin to be 10px. By creating a class that only encompases the botom-margin:10px; I can add it wherever it's needed.
I would suggest you're not using the cascade part of cascading style sheets, and you're probably choosing your class tokens for presentation rather than semantic value. These are common afflictions suffered by the tyro. Experience and the desire to follow best practice are the cure. cheers, gary