I don't really understand anything about fonts, as much as I have tried to read about them. I ultimately just wanted a font that kinda looked like it was written in a typewriter style, which also had clear math symbols to read. I found an example somewhere here on the stackexchange (see link below), used pdflatex to compile it, I thought it looked ok. But some of the math fonts, when using `siunitx` look squashed in the inline math mode. 

My minimum working example is this:

```
\documentclass[a4paper,openany]{book}

\usepackage[variablett]{lmodern}  % line 2  
\renewcommand*\familydefault{\ttdefault} % line 3
\usepackage{siunitx}

\sisetup{
    detect-all = true,
    detect-inline-family = text,
    detect-inline-weight = text
}

\begin{document}

\noindent normal text: [\SI{5}{\milli\meter\squared}] \\ 
inline math mode: $[\SI{5}{\milli\meter\squared}]$ \\
mm 

\end{document}

```

If I just use the default fonts, i.e. remove line 2 and 3, then use siunitx, the "mm" looks like the same font as the text. 

Can anyone help me prevent the text getting squashed like this, or suggest an alternative font that won't have this issue? 

Link: 
[\textbf does not work with cmvtt style](https://tex.stackexchange.com/questions/415914/textbf-does-not-work-with-cmvtt-style/415936?noredirect=1#comment1133482_415936)

EDIT: I edited the MWE with \sisetup but was not able to fix the issue.