koha-tmpl/intranet-tmpl/prog/css/select2.css

   1 .select2-container.subfield_not_filled {
   2     background-color: initial;
   3 }
   4
   5 .select2-container.subfield_not_filled .select2-choice {
   6     background: initial;
   7     background-color : #FFFF99;
   8 }