In order to have a better experience when linking to headlines based on
their ID, a patch[1] introduced a new CSS construct to add some space in
front of HTML tags with an id field. Therefore they would no longer be
hidden by a visible navbar.
This cause a regression bug by moving the rendered mathjax out of its
visible area. This patch fixes the problem by restricting the previous
change to headlines only.
[1]: commit c9af13cf34
Signed-off-by: Sheogorath <sheogorath@shivering-isles.com>