[Tex/LaTex] multicols within colorbox

boxescolormulticol

i'm trying to get a gray background for an entire multicols environment and get errors with this "minimal" working example:

\documentclass[11pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage{graphicx}
\usepackage[table,dvipsnames]{xcolor}
\usepackage{color}
\usepackage{listings}
\usepackage{multicol}
\usepackage[left=2.5cm,right=2.5cm]{geometry}

\begin{document}
  \setlength{\parindent}{0mm}
  \setlength{\parskip}{11pt}

  \begin{titlepage}
    \begin{center}
      \colorbox{gray}{
        \begin{multicols}{2}
          \begin{description}

            \item[xyz] \hfill \\
            description

            \item[xyz] \hfill \\
            description

            \columnbreak

            \item[xyz] \hfill \\
            description

            \item[xyz] \hfill \\
            description
          \end{description}
        \end{multicols}
      }
    \end{center}
  \end{titlepage}
\end{document}

This generates a lot of errors on the closing "}" from the colorbox that make no sense for me.
If I comment the colorbox out it compiles without problems.

Something I guess is similar I hit while going through the suggestions:
A version of colorbox that works inside math environments

Since one of the errormessages states that it's automatically creating a math environment/symbol i guess my problem is similar, though the answer to the question is just codesalad i don't understand and thus can't really use.

Any explained solution to either prevent LaTex to create a math-environment or getting a grey background under the multicol is highly appreciated.

Btw. i just started using LaTeX, so explanations are also highly appreciated.

Best Answer

\colorbox is an LR box like \mbox. You can not nest vertical material directly in such a box, use

  \noindent
  \colorbox{gray}{%
  \parbox{\dimexpr\textwidth-2\fboxsep\relax}{\begin{multicols}...
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