Aligning thick hlines and vlines with tabularray

Question

I wrote a table like in the following MWE, using tabularray:

\documentclass[11pt]{article}
\usepackage{tabularray}
\begin{document}
\begin{table}[ht]
\centering
    \begin{tblr}{
        hlines,
        vlines,
        hline{1,2,Z}={2pt},
        vline{1,2,Z}={2pt},
        hline{3}={1}{2pt},
        vline{3}={1}{2pt}
    }
 Alpha & Beta & Gamma \\
 Epsilon & Zeta & Eta \\
 Iota & Kappa & Lambda \\
\end{tblr}
\end{table}
\end{document}

with the following result:

As you can see, the thick horizontal and vertical lines aren't aligned with the thin ones. I would want the thin lines to come out of the center of the thick lines. How do I do that?

Answer 1

For information, here is a way to have to reach your goal with {NiceTabular} of nicematrix (you need several compilations).

\documentclass[11pt]{article}
\usepackage{nicematrix,tikz}
\begin{document}
\begin{table}[ht]
\centering
\begin{NiceTabular}{ccc}[hvlines,rules/width=2pt]
   Alpha & Beta & Gamma \
   Epsilon & \Block{2-2}{} Zeta & Eta \
   Iota    & Kappa & Lambda \
\CodeAfter
   \tikz \draw (3-|2) -- (3-|4) ; 
   \tikz \draw (2-|3) -- (4-|3) ; 
\end{NiceTabular}%
\end{table}
\end{document}