Post Content padding should match in the editor and front end

[kjellr]

Consolidating two existing issues into one, since they're tightly related: #144 and #5

Current issue

Currently, there's a mismatch between the way site padding behaves in the post/page editor and the frontend.

• In the editor, post content has no padding at all, regardless of its assigned alignment (default, wide, full).
• In the front-end, post content has appropriate default padding (since it's added to our default templates), but full-width items do not go to the screen edges.

Editor	Front End

Target appearance

Our ideal solution is:

• Post content has a default padding that matches between the post/page editor and the front end.
• When a top-level item in the post content is assigned to be "full-width" it should go all the way to the screen edges.

Upstream issues/PRs:

These issues would be solved universally with a solution to the following issue:

• Consider a root-level site padding solution that still lets some items go full-width gutenberg#35607
• Add outer padding support to the flow layout gutenberg#35919
• Alternative approach to the layout outer padding gutenberg#36214

[richtabor]

Are we thinking those issues would be solved for 5.9? If not, do we have a plan B?

[kjellr]

Yes, we'll figure this out. I think we'll get to a solution in WordPress/gutenberg#35607.

A fallback would be to add CSS to handle this, but honestly I think that defeats the purpose of Gutenberg providing the layout control.

@richtabor I'm curious if you've been dealing with this issue in any other themes?

[richtabor]

Yea, I’m seeing the exact issue. I’ve added a temporary negative margin hack to negate it, but its not awesome - nor is it a standardized solution that all themes would benefit from. If anything Gutenberg could work add the negative margin itself ha 🤷.

I’m hoping for a standard that every full width aligned block can be adopted into automatically without any interference from a theme.

[kjellr]

I'm going to mark this as resolved for now because #291 has merged. But we can re-open as needed.