\begin{table}
\centering
\begin{tblr}[         %% tabularray outer open
]                     %% tabularray outer close
{                     %% tabularray inner open
colspec={Q[]},
hline{2}={1}{solid, black, 0.05em},
hline{1}={1}{solid, black, 0.08em},
hline{4}={1}{solid, black, 0.08em},
}                     %% tabularray inner close
$y^2 = e^x$ \\
$-2$ \\
$-3.14$ \\
\end{tblr}
\end{table} 
