From old feedback: Reflect width in Editor | Cwicly
I posted this in Feature Request, but it could almost be bug.
It would be nice if, when editing a post or page, the editor styles reflected the width of the main body inherited from the template. As it is now, it always goes to 100%. In a section if you have that section 100% wide your left aligned blocks are right up against the edge of the screen. However, since the template has a 90% width, when you view live, they have the margin.