Background color

Although LilyPond does not allow to specify a background color, it is possible to give the illusion of a colored background by printing a large colored box under the score, as demonstrated here.

\version "2.24"

%% http://lsr.di.unimi.it/LSR/Item?id=699

%LSR after an idea by Trevor Daniels http://lists.gnu.org/archive/html/lilypond-user/2008-09/msg00083.html

\relative c'' {
 a1 a  a
 % place in bottom layer
 -\tweak layer #-1
 -\markup {
   \with-dimensions #'(0 . 0) #'(0 . 0)
   % specify color
   \with-color #(rgb-color 1 0.5 0.5)
   % specify size
   \filled-box #'(-1000 . 1000) #'(-1000 . 4000) #0
 }
 a
}