Protocol v23

[stephaniehobson]

We're going to do some major renovations to improve maintainability.

• Rename "title" to "heading"
• Rename "desc" to "body"
• Use CSS logical properties (start/end and block/inline)
  • Rename classes and mixins to reflect logical names
• Standardize our focus support by using :focus-visible instead of :focus.
• Fix the Sass mixed-decls warnings and un-pin the Sass version

Once that's done before publishing we need to:

• Review the unsupported experience and give it some basic styles/support.
• Make sure the Firefox theme didn't get broken.

Existing issues (not all the work is in issues yet)

Modernizing:

• Go all-in on CSS custom properties for themes, remove Sass variables #982 (note: I don't think we need to have removing the Sass variables as a goal for V23 for values that do not morph)
• Sass warnings generated by font mixins #998
• Refactor typography system to use CSS custom properties #1107
• Audit use of vendor prefix mixins #957

Renaming:

• Rename "title" to "heading" #668
• Update component classes to use new naming standards #448
• Confusing naming for theme spacing variables #701

Finished work

• Refactor spacing to use CSS custom properties (#982) #1114
• Remove deprecated feature card component #1113
• Simplify split component by removing pop options (#896) #1110
• Refactor color to use CSS custom properties (#982) #1109
• Refactor typography system to use CSS custom properties #1107
• Fix remaining mixed-decls warnings (Fix #998) #1117