[Plugin: Dynamic "To Top" Plugin] Problem in IE

Hi,
there’s a way to eliminate in the plugin the shading shadow when I hover mouse on the button? Shade works fine on Firefox and Chrome, while in IE the base color appears without shade and button appears full of a dark color.
I don’t know how to make changes in your filter…I’m not a developer, could you give me some alternative solution?
Thanks a lot…take a look here: http://www.robertorizzo.com

http://wordpress.org/extend/plugins/dynamic-to-top/