- the right-arrow wasn't highlighted on hover, which was
inconsistent with the other header items
- changed the user-menu items highlight color from #fff to #fafafa, which is
consistent across the header
- refactored the css to reduce specificity
- refactored css to use nesting in class names instead of nesting in
scss (as advocated by http://smacss.com) to reduce specificity and
to enhance readability
