Problems with vertically aligning to middle?

[RealXuChe]

I'm trying to put some code highlighted with minted in one cell, but I found it's hard to align to the middle vertically.

\documentclass{article}

\usepackage{xcolor}
\usepackage{minted}
\usepackage{tabularray}

\begin{document}

\begin{tblr}{|Q[m,c]|Q[c,m]|}
\hline
\fbox{\mintinline{python}{a=2}} & \fbox{(1)} \\
\hline
\end{tblr}

\end{document}

Result on my computer is:

It's obvious that the spacing above the code block is smaller than the one below.
Could anyone please help me middling this?

[lvjr]

There is no difference between vertical alignment t/m/b if every cell has only a single line. You can use adjustbox package to adjust the cells:

\documentclass{article}

\usepackage{xcolor}
\usepackage{tabularray}
\usepackage{adjustbox}

\begin{document}

\begin{tblr}{|Q[c]|Q[c]|}
\hline
\adjustbox{fbox,valign=m}{a=2} & \adjustbox{fbox,valign=m}{(1)} \\
\hline
\end{tblr}

\end{document}

[RealXuChe]

Thanks for helping! This seems to work fine for the case, so I tried to play with adjustbox more. I just copied your solution three times and changed fboxsep for each of them, and some weird thing happened:

\documentclass{article}

\usepackage{xcolor}
\usepackage{tabularray}
\usepackage{adjustbox}

\begin{document}

\begin{tblr}{|Q[c]|Q[c]|}
\hline
\adjustbox{fbox=0.4pt 0pt,valign=m}{\tt a=2} & \adjustbox{fbox,valign=m}{(1)} \\
\hline
\end{tblr}

\begin{tblr}{|Q[c]|Q[c]|}
\hline
\adjustbox{fbox,valign=m}{\tt a=2} & \adjustbox{fbox=0.4pt 0pt,valign=m}{(1)} \\
\hline
\end{tblr}

\begin{tblr}{|Q[c]|Q[c]|}
\hline
\adjustbox{fbox=0.4pt 0pt,valign=m}{\tt a=2} & \adjustbox{fbox=0.4pt 0pt,valign=m}{(1)} \\
\hline
\end{tblr}

\end{document}

If I only change the first column, everything's fine. When I set fboxsep of the second column, both columns will break. Setting both fboxsep will only make it worse.

I'm basically new to LaTeX. It's confusing for me that the order of the changed fbox will affect the result. I wonder why this would happen and how to fix it.

[lvjr]

By default, there is an invisible strut in every cell to give minimal height and depth for it (see \strut command in the answer of Herbert Voß). You can remove the struts by setting stretch=0.

\usepackage{xcolor}
\usepackage{tabularray}
\usepackage{adjustbox}

\begin{document}

\begin{tblr}{colspec={|Q[c]|Q[c]|},stretch=0}
\hline
\adjustbox{fbox=0.4pt 0pt,valign=m}{\tt a=2} & \adjustbox{fbox,valign=m}{(1)} \\
\hline
\end{tblr}

\begin{tblr}{colspec={|Q[c]|Q[c]|},stretch=0}
\hline
\adjustbox{fbox,valign=m}{\tt a=2} & \adjustbox{fbox=0.4pt 0pt,valign=m}{(1)} \\
\hline
\end{tblr}

\begin{tblr}{colspec={|Q[c]|Q[c]|},stretch=0}
\hline
\adjustbox{fbox=0.4pt 0pt,valign=m}{\tt a=2} & \adjustbox{fbox=0.4pt 0pt,valign=m}{(1)} \\
\hline
\end{tblr}

\end{document}

[hvoss49]

\documentclass{article}
\usepackage{tabularray}
\begin{document}

\begin{tblr}{|Q[c]|Q[c]|}\hline
\fbox{a=2\strut} & \fbox{(1)\strut} \\\hline
\end{tblr}

\end{document}

[RealXuChe]

I think I'd better have a deeper look at the TeX mechanism and try to figure it out. And thanks for all your help!