带有 mdframed 的垂直彩色标题

Question

我正在尝试创建这样的环境，但没有成功：

我所知道的是：

这个问题的完美答案是让标题有颜色，而文本脱离 mdframed 环境。这样做的原因是，如果您有太多文本（或大型方程式），mdframed 会因“overfull \vbox”而发疯。我的部分代码如下：

\documentclass[a4paper, 12pt]{article}


\usepackage[framemethod=TikZ]{mdframed}
\newcounter{solution}[section]
\renewcommand{\thesolution}{\arabic{section}.\arabic{solution}}

\newenvironment{solution}[1][]{%
    \refstepcounter{solution}

    % Always:
    \mdfsetup{leftmargin = 0.25cm, rightmargin = 0cm,
        innertopmargin = 0.25cm, linecolor = gray!50,
        linewidth = 2pt, topline = true, 
        frametitleaboveskip = \dimexpr-\ht\strutbox\relax}

    % 'if' condition (without title)
    \ifstrempty{#1}%
        {\mdfsetup{frametitle = {%
            \tikz[baseline = (current bounding box.east), 
            outer sep = 0pt]
            \node[anchor = east, rectangle, fill = gray!50]
            {\strut Soluci\'on};}}
        }
    % 'else' condition (with title)
        {\mdfsetup{frametitle = {%
            \tikz[baseline = (current bounding box.east), 
            outer sep = 0pt]
            \node[anchor = east, rectangle, fill= gray!50]
            {\strut Soluci\'on: #1};}}
        }
    
        
    \begin{mdframed}[]\relax}{%
    \end{mdframed}}

顺便说一下，我说的“发疯”是指：

感谢阅读！

Answer 1

正如 Ulrike 所建议的，可以轻松完成tcolorbox：

\documentclass[a4paper, 12pt]{article}
\usepackage{mwe}%for testing purpose only
\usepackage{tcolorbox}
\tcbuselibrary{skins, breakable}
\newtcolorbox{solution}[2][]{%
enhanced,breakable,
attach boxed title to top left,
left = 0.25cm, right = 0cm,
%frame hidden,
title={\strut Soluci\'on: #2},
colbacktitle=gray!50,
coltitle=black,fonttitle=\bfseries,
attach boxed title to top left={yshift=-\tcboxedtitleheight/2, xshift=4mm},
boxed title style={sharp corners,colframe=gray!50, boxsep=0pt},
top=\tcboxedtitleheight/2+2mm,
opacityframe=0, opacityback=0,
borderline horizontal={0.5mm}{0pt}{gray!50},
}
\begin{document}
\begin{solution}{Title of the solution}
Something something 
\end{solution}
\begin{solution}{Another solution}
It is also breakable

For testing purpose only: \blindtext[4]
\end{solution}
\end{document}

编辑：
如果标题为空则使用默认标题：

\documentclass[a4paper, 12pt]{article}
\usepackage{mwe}%for testing purpose only
\usepackage{etoolbox}
\usepackage{tcolorbox}
\tcbuselibrary{skins, breakable}
\newtcolorbox{solution}[2][]{%
enhanced,breakable,
attach boxed title to top left,
left = 0.25cm, right = 0cm,
%frame hidden,
title={\strut Soluci\'on: \ifstrempty{#2}{Default title}{#2}},
colbacktitle=gray!50,
coltitle=black,fonttitle=\bfseries,
attach boxed title to top left={yshift=-\tcboxedtitleheight/2, xshift=4mm},
boxed title style={sharp corners,colframe=gray!50, boxsep=0pt},
top=\tcboxedtitleheight/2+2mm,
opacityframe=0, opacityback=0,
borderline horizontal={0.5mm}{0pt}{gray!50},
}
\begin{document}
\begin{solution}{Title of the solution}
Something something 
\end{solution}
\begin{solution}{}
Something something 
\end{solution}
\begin{solution}{Another solution}
It is also breakable

For testing purpose only: \blindtext[4]
\end{solution}
\end{document}