% created using textables on Thu Mar 23 08:36:07 2023
\begin{tabular}{lcc}
\toprule 
\midrule 
{\color{red} hello} & \multicolumn{2}{r}{{\color{blue} world}} \\
 \cmidrule(lr){1-1} \cmidrule(lr){2-3} 
$\alpha$ & $\frac{1}{2}$ & $\sqrt{\frac{2}{3}}$ \\
\midrule 
\bottomrule 
\end{tabular}
