I modified the Cutline theme because I like black backgrounds for websites. Someone asked me for the code, so I decided to go through and take out all the changes and put them in the custom.css file. The CutlineNegative theme really only has a few minor tweaks, so you can also just download the .css file which you should use as your custom.css file.
http://bitfreedom.com/cutlinenegative
Here is an example of it that I use for my own blog: