Original post with updates :
http://forum.suprbay.org/showthread.php?tid=64016

v2.0
I tried to keep the code clean, there's a lot of comments (/* */) so it should be easy to tweak it by yourself if there something you don't like.

This CSS is made for Opera, but should be fully working with Firefox + Stylish.
Feel free to modify it to fit your browser.

Full CSS for Opera :
http://www.mediafire.com/?9gr4jfvpiztljh2 (yellow)
http://www.mediafire.com/?vx752s10v8worwl (blue)
Full CSS for Firefox :
http://www.mediafire.com/?kmm7focorfd5hef (yellow)
http://www.mediafire.com/?4d88mlbxkknn4q7 (blue)

Screen-shots :
http://img148.imageshack.us/img148/4346/1sbx.jpg

The PirateBay - Dark Clean Mesh :
The Pirate Bay - Dark Clean Mesh v2.0

The BayImg - Dark Clean Mesh :
The BayImg - Dark Clean Mesh v2.0