Template talk:Handbook sidebar
I hope the changes I've made here don't break other pages. It looked like someone had tried to add a margin earlier, but in a second 'style' attribute that was getting ignored; I added that in because I thought it would look better in combination with the change at Help:Editing where I put the sidebar after the header block. I used a smaller margin size, and also reduced the padding in the sidebar.
I don't know how to prevent the underline (bottom-border?) of Hx elements from crossing into the sidebar, or I'd change that too.