\documentclass{article}
\usepackage{fontspec}
\setmainfont{Noto Serif}
\usepackage{etoolbox} % \ifblank
\usepackage{xparse}   % Optional * and optional {} argument
\usepackage{calc} % \heightof
\usepackage{graphicx} % \reflectbox
\usepackage[svgnames]{xcolor}   % colors!
\usepackage{booktabs}
\usepackage{longtable}
\usepackage{hyperref}

\title{Reversed pilcrow in black/colored box}
\author{Benct Philip Jonsson}
\date{2019-12-05}

% Typeset a reverse pilcrow in a colored and/or framed box
%
% `\Pandoc`
% :   White reverse pilcrow in black box.
% `\Pandoc*`
% :   Black reverse pilcrow in white box with black frame.
% `\Pandoc{blue}`
% :   White reverse pilcrow in blue box.
% `\Pandoc*{blue}`
% :   Blue reverse pilcrow in white box with blue frame.
% `\Pandoc[yellow]{blue}`
% :   Yellow reverse pilcrow in blue box.
% `\Pandoc*[yellow]{blue}`
% :   Blue reverse pilcrow in yellow box with blue frame.
%
% In spite of the braces the second color is also optional!
%
% |    | Argument | Meaning   | Unframed (default) | Framed (default)
% |----|----------|-----------|--------------------|-------------------
% | #1 | * (star) | Framed?   | no star            | star
% | #2 | [color]  | Secondary | Foreground (white) | Background (page)
% | #3 | {color}  | Primary   | Background (black) | Foreground (black)
%
% If \Pandoc  (no star!)
% :     [#2] is foreground (text),
% :     {#3} is background (box) color.
% If \Pandoc* (with star), i.e. with frame
% :     [#2] is background (box),
% :     {#3} is foreground (text, frame) color.
%
% This command requires the packages
%           *graphicx*, *xcolor*, *xparse*, and *etoolbox*

% Helper commands to type less
\NewDocumentCommand{\pickMyColor}{ r() m r() m r() m }{
        \IfBooleanTF{#1}{% if framed
            \ifblank{#4}{\definecolor{#2}{named}{#3}}{\definecolor{#2}{named}{#4}}%
        }{% if not framed
            \ifblank{#6}{\definecolor{#2}{named}{#5}}{\definecolor{#2}{named}{#6}}%
        }%
}
\newcommand{\maybeFramebox}[3]{\IfBooleanTF{#1}{\fcolorbox{#3}{#2}}{\colorbox{#2}}}
\NewDocumentCommand{\Pandoc}{ s !O{} !G{} }{
    \pickMyColor(#1){PandocLogoForeground}(black){#3}(white){#2}%
    \pickMyColor(#1){PandocLogoBackground}(white){#2}(black){#3}%
    \reflectbox{%                       Reverse the pilcrow
        \maybeFramebox{#1}{PandocLogoBackground}{PandocLogoForeground}{%
            \color{PandocLogoForeground}%
            \makebox[\heightof{\P}][c]{\P}%
        }%
    }%
}

% Typeset a colored square with a reverse pilcrow in
% the complementary color of the box color:
%
% `\PandocBox`
% :   A black box with a white reverse pilcrow.
% `\PandocBox[blue]
% :   A blue box with a "-blue" reverse pilcrow.
%
% This command requires the packages *graphicx* and *xcolor*

\newcommand{\PandocBox}[1][black]{
    \reflectbox{\colorbox{#1}{\makebox[\heightof{\P}][c]{\color{-#1}\P}}}}

% Typeset a colored reverse pilcrow in a box of the same color
%
% `\PandocFrame`
% :   A black frame with a black reverse pilcrow.
% `\PandocFrame[blue]
% :   A blue frame with a blue reverse pilcrow.
%
% This command requires the packages *graphicx* and *xcolor*

\newcommand{\PandocFrame}[1][black]{
    \reflectbox{\color{#1}\fbox{\makebox[\heightof{\P}][c]{\P}}}}

% Helper command for examples
\newcommand{\textLarge}[1]{{\Large #1}}

\begin{document}

\maketitle

\hypertarget{latex}{%
\section*{LaTeX}\label{latex}}

In LaTeX you can, through the \emph{graphicx} package, produce a
reversed pilcrow with \texttt{\textbackslash{}reflectbox\{\textbackslash{}P\}}, thus reversing the
ordinary pilcrow of whatever font you are using.

The following isn't \emph{dead} simple, but satisfactory for a quite
sophisticated design:

\begin{verbatim}
---
mainfont: Noto Serif
header-includes:
  - |
    ````{=latex}
    \usepackage{graphicx}
    ````
---

\fbox{\Huge\makebox[1em][c]{\reflectbox{\P}}}

\colorbox{black}{\Huge\makebox[1em][c]{\reflectbox{\textcolor{white}{\P}}}}

\fbox{\textcolor{red}{\fbox{\Huge\makebox[1em][c]{\reflectbox{\P}}}} Made with Pandoc}
\end{verbatim}

Attached are three commands for typesetting a reverse pilcrow in
a colored and/or framed box, black/white by default but allowing
custom colors.
Note that the colors below are only examples.

\hypertarget{typeset-a-reverse-pilcrow-in-a-colored-andor-framed-box}{%
\subsection*{Typeset a reverse pilcrow in a colored and/or framed box}\label{typeset-a-reverse-pilcrow-in-a-colored-andor-framed-box}}

\begin{description}
\item[\texttt{\textbackslash{}Pandoc}]
White reverse pilcrow in black box.

\textLarge{\Pandoc}
\item[\texttt{\textbackslash{}Pandoc*}]
Black reverse pilcrow in white box with black frame.

\textLarge{\Pandoc*}
\item[\texttt{\textbackslash{}Pandoc\{DarkGreen\}}]
White reverse pilcrow in DarkGreen box.

\textLarge{\Pandoc{DarkGreen}}
\item[\texttt{\textbackslash{}Pandoc*\{DarkGreen\}}]
DarkGreen reverse pilcrow in white box with DarkGreen frame.

\textLarge{\Pandoc*{DarkGreen}}
\item[\texttt{\textbackslash{}Pandoc{[}Gold{]}\{DarkGreen\}}]
Gold reverse pilcrow in DarkGreen box.

\textLarge{\Pandoc[Gold]{DarkGreen}}
\item[\texttt{\textbackslash{}Pandoc*{[}Gold{]}\{DarkGreen\}}]
DarkGreen reverse pilcrow in Gold box with DarkGreen frame.

\textLarge{\Pandoc*[Gold]{DarkGreen}}
\end{description}

In spite of the braces the second color is also optional!

\begin{longtable}[]{@{}lllll@{}}
\toprule
& Argument & Meaning & Unframed (default) & Framed (default)\tabularnewline
\midrule
\endhead
\#1 & \texttt{*} (star) & Framed? & no star & star\tabularnewline
\#2 & \texttt{{[}color{]}} & Secondary & Foreground (white) & Background (page)\tabularnewline
\#3 & \texttt{\{color\}} & Primary & Background (black) & Foreground (black)\tabularnewline
\bottomrule
\end{longtable}

\begin{description}
\item[If \texttt{\textbackslash{}Pandoc} (no star!)]
\texttt{{[}\#2{]}} is foreground (text),

\texttt{\{\#3\}} is background (box) color.
\item[If \texttt{\textbackslash{}Pandoc*} (with star), i.e.~with frame]
\texttt{{[}\#2{]}} is background (box),

\texttt{\{\#3\}} is foreground (text, frame) color.
\end{description}

This command requires the packages \emph{graphicx}, \emph{xcolor},
\emph{xparse}, and \emph{etoolbox}

\hypertarget{typeset-a-colored-square-with-a-reverse-pilcrow-in-the-complementary-color}{%
\subsection*{Typeset a colored square with a reverse pilcrow in the complementary color}\label{typeset-a-colored-square-with-a-reverse-pilcrow-in-the-complementary-color}}

\begin{description}
\item[\texttt{\textbackslash{}PandocBox}]
A black box with a white reverse pilcrow.

\textLarge{\PandocBox}
\item[\texttt{\textbackslash{}PandocBox{[}Crimson{]}}]
A Crimson box with a ``-Crimson'' reverse pilcrow.

\textLarge{\PandocBox[Crimson]}
\end{description}

This command requires the packages \emph{graphicx} and \emph{xcolor}

\hypertarget{typeset-a-colored-reverse-pilcrow-in-a-box-of-the-same-color}{%
\subsection*{Typeset a colored reverse pilcrow in a box of the same color}\label{typeset-a-colored-reverse-pilcrow-in-a-box-of-the-same-color}}

\begin{description}
\item[\texttt{\textbackslash{}PandocFrame}]
A black frame with a black reverse pilcrow.

\textLarge{\PandocFrame}
\item[\texttt{\textbackslash{}PandocFrame{[}DarkGreen{]}}]
A DarkGreen frame with a DarkGreen reverse pilcrow.

\textLarge{\PandocFrame[DarkGreen]}
\end{description}

This command requires the packages \emph{graphicx} and \emph{xcolor}

\end{document}