Using Firefox and Firebug you can watch something. It seems there are at least 7 CSS for a layout.
I don't use Firebug. Several browsers have tools/developer modes, "inspectors" if you will. You can right-click on any element to get font size, colors, font family, other "spacing", etc.
Oh, yes, there is default developer tool embed in Firefox as of some version. I installed firebug at old time then continue using it, there is not so many reasons for it.
There are tons of overridden unused definition in CSSs...