Borders with different widths

Question

I'm looking for a way to draw a border on the top and left, but they should have different widths. I've been trying to do this using the mdframed package, but there doesn't seem to be an easy way to draw a border on the left that has a different width from the border at the top.

\documentclass{article}
\usepackage{mdframed}
\usepackage{lipsum}

\newmdenv[rightline=false,bottomline=false]{topbot}

\begin{document}

\begin{topbot}
\subsection*{This is the title}
\end{topbot}
\lipsum[2]

\end{document}

This is what I have:

And this is what I am looking for:

Answer 1

Although I think this is not the way to change section format, here you have a solution for OP's example with tcolorbox.

\documentclass{article}
\usepackage{tcolorbox}
\usepackage{lipsum}

\newtcolorbox{topbot}[1][]{leftrule=5pt, toprule=.5pt, rightrule=0pt, bottomrule=0pt, colback=white, notitle, sharp corners, #1}

\begin{document}

\begin{topbot}
\subsection*{This is the title}
\end{topbot}
\lipsum[2]

\end{document}

Update:

If a fancy format for unnumbered sections is what is desired. titlesec provides better solutions than a mdframed or tcolorbox environment containing a subsection command.

\documentclass{article}
\usepackage{xcolor}
\usepackage[calcwidth,explicit]{titlesec}
\usepackage{lipsum}

\titleformat{name=\subsection, numberless}
  {\titlerule\normalfont\large\bfseries}
  {\colorbox{black}{\parbox{1mm}{\strut}}}
  {.5em}{#1}

\titlespacing*{\subsection}{0pt}{3.25ex plus 1ex minus .2ex}{1.5ex plus .2ex}

\begin{document}

\subsection*{This is the title}

\lipsum[2]

\end{document}