add alignfull image block caption rules to constrain caption width within main column

[benlk]

Desired appearance:

Present-day:

the fix:

.wp-block-image.alignwide figcaption,
.wp-block-image.alignfull figcaption {
   max-width: (the column width);
   margin: 0 auto;
}

will require testing on posts and pages using:

• one-column template
• mstoday's custom template
• two-column template
• fullwidth template

[benlk]

Another screenshot from the reporting site, this time on mobile:

[MirandaEcho]

Add alignfull/alignwide image block caption rules to constrain caption width

[benlk]

From discussion around #1843 and INN/umbrella-mstoday#54:

I would really like to just redo how Largo does the .entry-content and page layout, switching to CSS Grid or at least having the main column have a defined width that isn't made by whittling the viewport down with padding on both #page and .entry-content and sometimes other elements.

[benlk]

As noted in INN/umbrella-ipbs#41, CSS Grid will not work until elements are able to automatically span rows in a column layout.