I would like to do the following layout using blueprint css
Page Width = 960px
<- 20px -> <------- 600px -------> <- 20px -> <--- 300px ---> <- 20px ->
left main content middle right rail right
gutter gutter (ad unit) gutter
What would the appropriate column width, margin-width and number of columns to make this work?
I am trying to do this with 10px columns and 10px margin but it ends up with 30px as the middle gutter (one full column + margin from the right)