suggested fix

this works by only styling the nav button when it should exist (when
.shelved or  .unshelved), which means we don't need to alter the display
style.  it is either there or not in full
test to see if z-index is the issue
oh for svg support
test for position
retest z-index as root issue
ensure color is gone on sig
quick test by marking it red
test positioning issue
test the button element html dom prase error
test replacement of button for link
test that the element even exists
reset the button to be displayed normally
testing for a js error by reordering
Merge pull request #172 from washingtonstateuniversity/fixes__issue_167

Fixes  issue 167