[Tex/LaTex] Line down the side of the page

longtablepage-breakingtables

At the moment I'm using the {tabular} environment to distinguish examples in a document I'm writing:

\begin{tabular}{r|p{11cm}}
\emph{Example} & [Lots of text and equations]
\end{tabular}

It makes it so that there's a nice line running down the left side of my page over the course of the example. The only problem is that it doesn't behave well with page breaks. I know the package longtable works for continuing tables onto several pages but since I have everything in one table entry, it doesn't work for me.

I realise I'm completely misusing {tabular} and am looking for an environment that will give me the same effect, but will continue the effect onto successive pages.

Best Answer

Two simple examples showing two possibilities: one with mdframed and the other one with tcolorbox; the advantage of these packages over framed is that they offer endless customization possibilities with a simple key=value interface:

\documentclass{article}
\usepackage[a5paper,paperwidth=18cm]{geometry}% just for the example
\usepackage{amsthm}
\usepackage[framemethod=tikz]{mdframed}
\usepackage[most]{tcolorbox}
\usepackage{lipsum}% just to generate text for the example

\newmdtheoremenv[
hidealllines=true,
leftline=true,
innertopmargin=0pt,
innerbottommargin=0pt,
linewidth=4pt,
linecolor=gray!40,
innerrightmargin=0pt,
innertopmargin=-6pt,
]{examplei}{Example}

\newtcolorbox{exampleii}{
freelance,
breakable,
width=\dimexpr\textwidth+28pt\relax,
before=\par\vspace{\bigskipamount}\noindent,
enlarge left by=-14pt,
overlay unbroken and first={
  \node[
  anchor=north east,
  inner xsep=8pt,
  xshift=8pt,
  rounded corners=5pt,
  font=\bfseries,
  fill=white] at ([xshift=-0.2cm]frame.north west) (tit) {\strut Example:};
  \draw[
  line width=3pt,
  rounded corners=5pt,gray
  ] ([xshift=4pt]frame.north west) -- ([xshift=4pt]frame.south west);
},
overlay middle and last={
  \draw[
  line width=3pt,
  rounded corners=5pt,gray
  ] ([xshift=4pt]frame.north west) -- ([xshift=4pt]frame.south west);
},
frame code={},
interior code={},
top=0pt,
bottom=0pt
}

\begin{document}

\lipsum[1]
\begin{examplei}
\lipsum[4]
\end{examplei}
\lipsum[4]
\begin{examplei}
\lipsum[1-2]
\end{examplei}
\lipsum[1-3]
\begin{exampleii}
\lipsum[4]
\end{exampleii}
\lipsum[1]
\begin{exampleii}
\lipsum[4-6]
\end{exampleii}
\lipsum[4-5]

\end{document}

enter image description here

The page layout was changed just for the example.

You can also take a look at the answer to Typesetting a definition for more examples and variations (the code in that answer can be easily adapted to produce the label "Example" instead of "Definition").

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