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There are several ways involved in changing the buttons.

1. Some of the buttons are created in css and changing the color is easy by just changing the color code. 

2. Others have been created as images and those images might be able to be edited in something like photoshop to a different color.

3. Some are icons from icon suppliers for which you can just apply a code to it in css while others are much more difficult to do because they involve vectors i believe they call them, which is a proprietary format...

I dont know it all but basically that is what i understand the main options are.  If i am wrong someone please correct me :)

Patrick sorry to lose you if you have to switch platforms, but we all understand you have to do whats best for you and your users.    If you leave we hope to see you back here someday and also watch for something new as well...  :0 )

Best of luck always...

Dave :)