How to give color inside $\Box$

Question

I want gray inside $\Box$. How can we do that? I will use this as a caption of my figure like

\caption{ $\Box$ denotes ...}

Probably better to use something like \fcolorbox{black}{gray}{\ } or similar. — daleif, May 31 '21 at 08:27
xcolor, though {\fboxsep=0pt\fbox{\color{gray}\rule{3mm}{3mm}}} might be better, more squareish. Please note you should never provide sniplets like this, always use minimal examples including document class and relevant preamble. Then we know what you are working with. — daleif, May 31 '21 at 08:49

score 2 · Accepted Answer · answered May 31 '21 at 08:58

The easiest method is probably something like

\documentclass[a4paper]{article}
\usepackage{xcolor}
\begin{document}
{\fboxsep=0pt\fbox{\color{gray}\rule{3mm}{3mm}}}
\end{document}

\fbox has some padding, which we locally remove by setting \fboxsep to zero.

score 1 · Answer 2 · answered May 31 '21 at 12:24

You possibly want squares with different colors. The following \csq command will change size according to the context.

\documentclass{article}
\usepackage{xcolor}
\NewDocumentCommand{\csq}{om}{%
  % colored square
  % #1 = color model (optional)
  % #2 = color spec
  \IfNoValueTF{#1}{%
    \textcolor{#2}{\rule{1.2ex}{1.2ex}}%
  }{%
    \textcolor[#1]{#2}{\rule{1.2ex}{1.2ex}}%
  }%
}
\begin{document}
\csq{gray} denotes something
\csq[rgb]{0.1,0.3,0.9} denotes something else
\csq{red!40!blue} something completely different
{\Large\csq{gray} Large}
\end{document}

If you're running LaTeX before the 2020-10-01 release, you also need

\usepackage{xparse}

How to give color inside $\Box$

2 Answers2