% Create a rectangle of the full size
a := unitsquare xyscaled(\overlaywidth,\overlayheight);
% Randomize it a bit
-b := a randomized 10pt ;
+b := a randomized (\overlaywidth / 25) ;
% And draw it
drawoptions (withpen pencircle scaled .75mm withcolor black) ;
draw b;
% A boxed variant with the width forced to page width. This is used in
% \startrans, since the content somehow doesn't scale the box around it
% properly.
-\defineframedtext[wideboxed][background=box,frame=off,width=\textwidth]
+\defineframedtext[wideboxed][background=box,frame=off,width=\textwidth,offset=.02\textwidth]
% Install the lambda calculus pretty-printer, as defined in pret-lam.lua.
\installprettytype [LAM] [LAM]