Revert "Hide header on all mobile pages"
Revert "Hide header on all mobile pages"

This reverts commit 4047b34b2a09f986505bb104d123088bb8a410de.

jazzband/website,jazzband/website,jazzband/website,jazzband/jazzband-site,jazzband/jazzband-site,jazzband/website,jazzband/site,jazzband/site