In the attachment is a CSS File. This File includes all CSS wich I used, to get the Theme 'Graphite' ready for mobile.
Maybe you could enter it in the custom CSS and all works fine, if you only changed some color or fonts.
If you changed the width or floating of some Elements you might have to fix something arround...
I can give you no Warranty, if this work. But maybe you can find some Hacks or fixes for some Themes and post it here :D
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