3
I'm not real sure if this is what you are asking or need but here goes.
The block title style is in your style.css of the theme you are trying to modify. If you look in there you will find it in the areas of(normally) td#mainmenu, td#usermenu
td#rightcolumn, td#centerCcolumn, td#centerLcolumn and td#centerRcolumn and should look something like this.
td#centerCcolumn div.blocktitle (example)
the content for the blocks (block content)will be
td#centerLcolumn div.blockcontent (example)
the module block content is either controlled by the #div.content styles or a combination of them and the other styles in the style.css. However, some modules come with additional .css file(s) in the module package(directory) you are trying to modify.
Quest