Text Formatting ⇒ Left-align theorem numbers

[bstex]

Hi.
I'm using the ntheorem package but I can't force the theorem numbers to be left-aligned.
As you can see in my MWE, the theorem numbers are right-aligned by default, but I need them to be left-aligned. It is a very small detail, but it doesn't look very nice when theorems have bigger numbers, for example 0.150 etc.

My MWE:

Code: Select all

\documentclass[a4paper]{book}
\usepackage{showframe}
\usepackage[top=2.5cm,bottom=2.5cm,inner=3cm,outer=2cm,headsep=10pt]{geometry}
\usepackage{lipsum}

\usepackage[standard]{ntheorem}
\theoremstyle{margin}
\theoremindent3em
\theorembodyfont{\normalfont}
\newtheorem{MyTheorem}{\hspace*{-0.5em}}[chapter]

\begin{document}

\begin{MyTheorem}
\lipsum[2-2]
\end{MyTheorem}

\begin{MyTheorem}
\lipsum[2-2]
\end{MyTheorem}

\begin{MyTheorem}
\lipsum[2-2]
\end{MyTheorem}

\begin{MyTheorem}
\lipsum[2-2]
\end{MyTheorem}

\begin{MyTheorem}
\lipsum[2-2]
\end{MyTheorem}

\begin{MyTheorem}
\lipsum[2-2]
\end{MyTheorem}

\begin{MyTheorem}
\lipsum[2-2]
\end{MyTheorem}

\begin{MyTheorem}
\lipsum[2-2]
\end{MyTheorem}

\begin{MyTheorem}
\lipsum[2-2]
\end{MyTheorem}

\begin{MyTheorem}
\lipsum[2-2]
\end{MyTheorem}

\begin{MyTheorem}
\lipsum[2-2]
\end{MyTheorem}

\begin{MyTheorem}
\lipsum[2-2]
\end{MyTheorem}

\begin{MyTheorem}
\lipsum[2-2]
\end{MyTheorem}

\begin{MyTheorem}
\lipsum[2-2]
\end{MyTheorem}

\begin{MyTheorem}
\lipsum[2-2]
\end{MyTheorem}

\end{document}

Any help, please? I have tried so many things with this package.

[Johannes_B]

That should give a first clue.
https://tex.stackexchange.com/a/218302/37907

[bstex]

I have read this post, but I closed the tab because I couldn't do it with the ntheorem package.
Little did I know that I had to change all my theorems preamble code and not use the ntheorem.
Thank you very much!

[Stefan Kottwitz]

Hi,

you postest a very good minimal example!

So fur sure we can achieve that. Here is a suggestion using \makebox for left alignment:

Code: Select all

\makeatletter
\newtheoremstyle{leftalign}%
  {\item[\theorem@headerfont \llap{\makebox[1.6em][l]{##2}}%
    \hskip\labelsep ##1\theorem@separator]}%
  {\item[\theorem@headerfont \llap{\makebox[1.6em][l]{##2}}%
    \hskip\labelsep ##1\ (##3)\theorem@separator]}
\makeatother
\theoremstyle{leftalign}

Stefan

[bstex]

I'll try your solution too.
Thank you very much, Stefan.

[bstex]

Your solution is excellent with the ntheorem package.
Thank you so much!