Archeo: Try new root padding alignments

[scruffian]

Changes proposed in this Pull Request:

This tries implementing the root padding alignment rules proposed in WordPress/gutenberg#42085. This means we can remove the alignment CSS.

Comparison

Before:	After:

Related issue(s):

WordPress/gutenberg#42085

[mikachan]

It looks like the new root padding alignments are working in most cases, apart from blocks nested in a full-width group block:

This PR:

Trunk (with alignment CSS & no root padding set):

[scruffian]

I'm not sure that the behaviour in trunk is desirable anyway, I think this is a fair compromise.

[mikachan]

Ah OK, I guess I was basing the intended gap on the wording in this test markup ('should have a gap between it and the edge'), and it seemed to be one of the biggest differences from the previous behaviour.

If these current gaps aren't ideal (and I would assume 'full width' should have no gaps between the container and the edge anyway) then the root padding seems to be working well 👍

[MaggieCabrera]

It looks like this will need some adjustments in Archeo, the text in the home page is not aligned anymore:

Before	After

[scruffian]

Good catch, thanks. I've zeroed some of the paddings here so that they match:

[vcanales]

This LGTM 🚢