greyarrow.tex

%http://tex.stackexchange.com/questions/50877/excursus-environment-using-mdframed-issue-with-page-breaks
\tikzset{
   excursus arrow/.style={%
    line width=2pt,
    draw=gray!40,
    rounded corners=2ex,
   },
   excursus head/.style={
    fill=white,
    font=\bfseries\sffamily,
    text=gray!80,
    anchor=base west,
   },
}

\mdfdefinestyle{mysquare}{%
  singleextra={%
   \path let \p1=(P), \p2=(O) in (\x2,\y1) coordinate (Q);%
   \path let \p1=(Q), \p2=(O) in (\x1,{(\y1-\y2)/2}) coordinate (M);%
   \path [excursus arrow, round cap-to]%
   ($(O)+(5em,0ex)$) -| (M) |- %
   ($(Q)+(12em,0ex)$) .. controls +(0:16em) and +(185:6em) .. %
   ++(23em,2ex);%
   \node [excursus head] at ($(Q)+(2.5em,-0.75pt)$) {Solution};},
  firstextra={%
   \path let \p1=(P), \p2=(O) in (\x2,\y1) coordinate (Q);
   \path [excursus arrow,-to]
   (O) |- %
   ($(Q)+(12em,0ex)$) .. controls +(0:16em) and +(185:6em) .. %
    ++(23em,2ex);
   \node [excursus head] at ($(Q)+(2.5em,-2pt)$) {Solution};
  },
  secondextra={%
   \path let \p1=(P), \p2=(O) in (\x2,\y1) coordinate (Q);
   \path [excursus arrow,round cap-]
   ($(O)+(5em,0ex)$) -| (Q);
  },
  middleextra={%
   \path let \p1=(P), \p2=(O) in (\x2,\y1) coordinate (Q);
   \path [excursus arrow](O) -- (Q);
 },
 middlelinewidth=2.5em,middlelinecolor=white,
 hidealllines=true,topline=true,
 innertopmargin=0.5ex,
 innerbottommargin=2.5ex,
 innerrightmargin=2pt,
 innerleftmargin=2ex,
 skipabove=0.87\baselineskip,
 skipbelow=0.62\baselineskip,
}