lucy24 - 1:35 am on Jul 9, 2011 (gmt 0)
Whew. Had to draw a picture to see what you're aiming at ;)
Quick-and-dirty answer: Padding is part of the object. The border runs along the entire object, just like a margin. There's no distinction between the border of the "real" part and the border that adjoins the padding. The w3c folks have all kinds of pretty pictures [w3.org] illustrating the point. (The ones in the "tables" chapter are actually prettier, but would be TMI.)
If you put the text inside a span, you can give it a border of its own which would only apply to the actual text, but this is iffy. Would the text ever overflow to a second line?