% Don't break the line that "Proof." is on.
\setbeamertemplate{proof begin}{
- \usebeamerfont*{block title}
- \usebeamercolor[fg]{block title}
+ \usebeamerfont*{proof title}
+ \usebeamercolor[fg]{proof title}
\insertproofname
\usebeamerfont*{block body}
\usebeamercolor[fg]{block body}