Grey border around the whole page

Question

I am typesetting novels in Latex and I would like to include a 'if you like this, why not try' section at the back.

Such sections are normally formatted like this:

With a nice grey border around the page, that indicates this section is differnet. It's normally visible from the side as well:

How can I achive this effect in Latex? (personally I'd be fine with doing it post-hoc in a pdf editor, but I don't know how to do that either)

Answer 1

Same result, but done at the package level, using tikz pagenodes, and setting the border command as the page header with fancyhdr, so you can add in other header material if you need to.

Perhaps easier to maintain and modify, semantically speaking, depending on your coding style. Only two variables, colour and line width (with the "frame's" given x- and y-shift of 0).

I find no additional overhead loading tikz, so this solution may depend on your system constraints (if any).

MWE

\documentclass{article}
\usepackage{tikz}
\usepackage{tikzpagenodes}
\usepackage{fancyhdr}
\usepackage{lipsum}

\newcommand{\gborder}{\tikz[remember picture,overlay] 
    \draw [black!10!blue!20,line width=18mm]
    (current page.south west)
    rectangle
    (current page.north east)
    ;}

\pagestyle{fancy}
\fancyhead{}
\fancyfoot{}
\fancyhead[C]{\gborder}
\renewcommand{\headrule}{}

\begin{document}

\section{A}
\lipsum[1-10]
\section{B}
\lipsum[1-10]
\end{document}

Answer 2

LaTeX has hooks for every page (e.g. shipout/background). This one expect picture commands, eg \put the picture (0,0) is in the topleft corner, see texdoc ltshipout-doc. With this it is fairly simple to build fixed backgrounds, e.g.

\documentclass{article}

\usepackage{xcolor,kantlipsum}

\AddToHook{shipout/background}{%
  \linethickness{20pt}%
  \color{black!25}%
  \put(0,-10pt){\line(1,0){\paperwidth}}%
  \put(10pt,0){\line(0,-1){\paperheight}}%
  \put(0,-10pt){\line(1,0){\paperwidth}}%
  \put(\paperwidth-10pt,-\paperheight){\line(0,1){\paperheight}}%
  \put(\paperwidth,-\paperheight+10pt){\line(-1,0){\paperwidth}}%
  }

\begin{document}

\kant

\end{document}