fix: CMD-79 navbar expanded can overflow header

[wesleyboar]

Overview

• Resolve migration mistake we didn't catch — near duplicate code.
• Fix edge-case-become-common-case* of dropdown CMS nav overflowing header.

^{* Edge-case because most CMS's haven't had the newer Core-Styles yet and TACC has used navbar width that avoids the bug. Become-common-case because more CMS's are getting the newer Core-Styles and TACC experienced the bug during development of TACC/tup-ui#416.}

Related

• CMD-79

Changes

• merges near-duplicate code
• changes height to min-height
• adds code to avoid logo moving on navbar expand/collapse

Testing & UI

before.mov

after.mov