\setbeamerfont{subtitle}{size=\normalsize}
\setbeamerfont{block body}{shape=\upshape}
-\setbeamerfont{block title}{shape=\upshape,series=\bfseries}
+\setbeamerfont{block title}{size={},shape=\upshape,series=\bfseries}
% Use slightly more leading than normal.
\linespread{1.1}