\documentclass[10pt,a4,landscape]{article}

% \usepackage[cam,a4,center,info,]{crop} % frame
\usepackage[height=20cm,width=25.7cm,noheadfoot,landscape]{geometry} % A4 - 210×297 mm

\usepackage[T1]{fontenc}
\usepackage{multicol}
\usepackage{color}
\usepackage{url}
\usepackage{lastpage}

\usepackage{hyperref}
\hypersetup{
  pdftitle={i3 Reference Card},
  pdfauthor={\textcopyright\ Zeus Panchenko},
  pdfkeywords={i3, refcard},
  pdfsubject={based on http://i3.zekjur.net/docs/userguide.html},
  pdfpagemode={FullScreen}}

\definecolor{lightgray}{gray}{0.7}

\pagestyle{empty}

\setlength{\parindent}{0in}
\setlength{\columnseprule}{0.5pt}
\setlength{\columnsep}{20pt}

\newcommand{\RefCardTitle}[2]
{\centering{\Large{\textbf{i3 Reference Card (#1/#2)\\
        {\scriptsize{\url{http://i3.zekjur.net/docs/userguide.html}}}}}}
  \vspace{1mm}}


\newcommand{\RefCardSec}[1] {\vspace{2mm} \raggedright {\vspace{0.5mm}
    \colorbox{lightgray} {\makebox[0.31\textwidth][l]
      {\Large{\textsc{\textsf{\textbf{\color{black}#1}}}}}}
    \vspace{0.5mm}}}

\newcommand{\RefCardRow}[2] {\normalsize{\textbf{\texttt{#1}}}
  \hspace{\stretch{1}} \raggedleft{\small{\textnormal{#2}}} \\}

\begin{document}

\centering

\begin{multicols}{3}
  \RefCardTitle{\thepage}{\pageref{LastPage}}

  \RefCardSec{Moving around}

  \RefCardRow{Mod1+Enter}{open new terminal}
  \RefCardRow{Mod1+j}{focus (left)}
  \RefCardRow{Mod1+k}{focus (down)}
  \RefCardRow{Mod1+l}{focus (up)}
  \RefCardRow{Mod1+;}{focus (right)}
  \RefCardRow{Mod1+Shift+j}{move window (left)}
  \RefCardRow{Mod1+Shift+k}{move window (down)}
  \RefCardRow{Mod1+Shift+l}{move window (up)}
  \RefCardRow{Mod1+Shift+;}{move window (right)}
  \RefCardRow{Mod1+Control+j}{snap (left)}
  \RefCardRow{Mod1+Control+k}{snap (down)}
  \RefCardRow{Mod1+Control+l}{snap (up)}
  \RefCardRow{Mod1+Control+;}{snap (right)}
  \RefCardRow{Mod1+Shift+q}{kill a window}
  \RefCardRow{Mod1+Shift+<number>}{move a window to another workspace}


  \RefCardSec{Changing container modes}

  \RefCardRow{Mod1+e}{default}
  \RefCardRow{Mod1+h}{stacking}
  \RefCardRow{Mod1+w}{tabbed}
  \RefCardRow{Mod1+Shift+f}{global fullscreen}
  \RefCardRow{Mod1+f}{toggle fullscreen}
  \RefCardRow{Mod1+Shift+Space}{toggle floating}
  \RefCardRow{Mod1+<Mouse>}{drag floating}

  \RefCardSec{Opening other applications}

  \RefCardRow{Mod1+v}{open application launcher (dmenu)}

  \RefCardSec{Using workspaces}

  \RefCardRow{Mod1+<number>}{switch to another workspace}

  \RefCardSec{Restarting i3 inplace}

  \RefCardRow{Mod1+Shift+r}{restart i3 inplace}

  \RefCardSec{Exiting i3}

  \RefCardRow{Mod1+Shift+e}{exit i3}

  \vspace{1cm}
  \tiny{
    \begin{center}
      Copyright \copyright 2009, Michael Stapelberg \\
      All rights reserved. \\
      Designed by Zeus Panchenko
    \end{center}
      Permission is granted to copy, distribute and/or modify this
      document provided the copyright notice and this permission
      notice are preserved on all copies.}

\end{multicols}

\end{document}