Sizing RSS subscribe button

I have three wordpress blogs, all with the Add To Any subscription plugin activated. I’ve added an rss button to the widget on each. On this blog, the button is a normal size and works well with its surroundings; but on this blog the button is much too large. Is there a place where I need to make an adjustment or is it just the way the button interacts with the theme? The button both originated from the same original file, but I altered the one to give it a black background. I made no other changes to it. Any (detailed) help for this novice?