Boxing and coloring background of text

Question

how can I easily make a box like this, set its width and the white border around it?

(Ignore the text inside.)

Answer 1

Here is way with tcolorbox and the borderline= option.

\documentclass{article}

\usepackage[most]{tcolorbox}
\usepackage{blindtext}
\begin{document}

\begin{tcolorbox}[enhanced jigsaw,
    sharp corners,
    boxrule=0.5pt, 
    colback=red!30!white,   
    borderline={0.5pt}{-2pt}{black,solid} % 0.5pt linewith, -2pt outside, black solid linestyle
 ]
\blindtext
\end{tcolorbox}

\end{document}

Answer 2

Here is a basic implementation that uses a key-value approach to setting the width and background colour:

\documentclass{article}
\usepackage{xcolor,keyval}
\usepackage[nopar]{lipsum}% Just for this example
\makeatletter
\definecolor{pinkish}{rgb}{0.96,0.80,0.80}
\newlength{@mcb@width}
\define@key{mcb}{bg}{\def@mcb@bg{#1}}
\define@key{mcb}{width}{\setlength@mcb@width{#1}}
\newcommand{\mycolorbox}[2][]{{%
  \setkeys{mcb}{width=0.5\linewidth,bg=pinkish,#1}%
  \fbox{\colorbox{@mcb@bg}{\begin{minipage}{@mcb@width}
    \strut#2\strut
  \end{minipage}}}
}}
\makeatother
\begin{document}
\mycolorbox{something}
\mycolorbox[width=.3\linewidth]{something}
\mycolorbox[bg=blue!40!white]{something}
\mycolorbox[bg=green!15!white,width=.7\linewidth]{\lipsum[1]}
\end{document}

\struts are used in an attempt to achieve a more consistent baseline height/depth at the top/bottom of the minipage construction.

One could also use a tabular construction, if needed.