and modify the music-project layout to display those orphan tracks.

also fix header that was wrong.
add styles for titles with backlink.
& other changes (see diff, i'm lazy)

add go back link to the heading

instead of list use div.post-header-info (list was not right)

and convert tabs to spaces :p

also snippet that makes art menu is now separated as mixin (very
powerful thing, btw).