Increased font size to decrease chars-per-line (SC 1.4.8) and increase
tap target size.
Pad the nav links more and add some extra space between them to meet SC
2.5.5.
Fixing the misaligned inline nav using "inline-block" also made it
obvious that I can simplify compound selectors. The max number of
compound selectors has dropped from 4 to 2. Update stylelint configs to
reflect this.
Also fix containment to reflect a prior change (webmentions are a
section, not a footer.)
