I am also looking to make my donate button match the other buttons! I tried messing with the code @creedon provided for OP, but was unsuccessful.
Buttons I like are on the homepage: http://amepstein.com and buttons I want to be bigger / look like those are at http://amepstein.com/gifts
Or even better yet--is there a way to put the donate button link / code in a regular button or image so I can make them more like cards?
TIA!