This makes negative margins on rows the default, not just in containers, and adds padding to body to compensate for the negative margin on narrow viewports. Why do this?
- Consistent row behavior across all viewports and grid tiers
- Consistent row behavior within a variety of components that aren't containers
- Simpler styling for completely fluid layouts (those that go edge to edge)
This would fix #9565 (closed), #9605 (closed), #9664 (closed), and a few other issues I believe.