This style makes the email drafting/reading area in Gmail full width. This is nice, especially if you have a lower resolution screen.
I admit, this code is potentially confusing, but if you take a look at the CSS, you should see that I've commented everything out and all you'll have to do is uncomment any elements you'd like to include. If you use this style (making the email area full-width), I'd recommend that you leave the "bonus" context sensitive stuff disabled, as otherwise it potentially gets in the way of your reading your email.
Originally inspired at the same time as Gmail (old version) - navigation box (width mod) and Gmail (old version) - navigation box (float).