% add tikz and a bunch of tikz foo
\usepackage{tikz}
\usetikzlibrary{shapes,shapes.misc,backgrounds,fit,positioning}
-\tikzstyle{every picture}+=[remember picture]
+\tikzstyle{every picture}+=[overlay,remember picture]
% add functions to circle parts of slides (e.g., in tables)
\newcommand\marktopleft[1]{%
\fontsize{#1}{2\centertxtlen}\selectfont
\e{#2}
-}
-% \end{center}
+ }
}