Not a problem now but might hit us later on.
When you visit Special: Nearby in Vector http://localhost:8888/w/index.php/Special:Nearby?useskin=vector
This pulls in some very generic but visible rules around styling a nav element that shouldn't be pulled in demonstrated by running this code:
$( '<nav>' ).prependTo( 'body' )
There are undoubtably some skins using a nav tag.