\setbeamercolor{background canvas}{bg=mjobg}
\setbeamercolor{title}{fg=mjohead}
+
\setbeamercolor{structure}{fg=mjotext}
+\setbeamercolor{normal text}{fg=mjotext}
\setbeamercolor{block title}{fg=mjohead}
+\setbeamercolor{proof title}{fg=mjotext}
\setbeamercolor{block body}{fg=mjotext}
\setbeamercolor{frametitle}{fg=mjotitle}