Admin panel code

I asked before but topic was closed and I got no answer so I will ask again:
I am creating new script(also open source) and this is my first time to design user interface. I checked lot of admin panels from lot of scripts and I find WordPress most logical and user friendly.
I check all my designs in FF and IE, but I don’t have Linux installed or Mac to check on them, too.
I want to know if I am allowed to use part of WordPress admin panel code as basic for user interface architecture and trusted html and css for all browsers.
Let me know, thanks.