Cleanup tip test, starting with markup and js (1/2)...

Instead of a box test, we're actually looking for
a bar test.

Add visual-test classes. Rename menu to list,
clean up some debris. Make body the edge test
container. And we're done.
Cleanup tip test, refine and refactor base scss (2/2)....

Make list more flexible, try to support ul/ol and
nav elements. Model the new bar UI after it.

Move and refactor edge styles into edge from
tip-specific sheet.

Add new color and size vars. Refactor all em sizes
to be pseudo-dynamic around text size var.

Add visual-test classes. Rename menu to list,
clean up some debris. Make body the edge test
container. And we're done.