After \begin{document} I'm using this package

\usepackage[dvipsnames]{xcolor}

I also post the code I'm using into the document:

\resizebox{\textwidth}{!}{ \begin{tabular}{|l|c|} \hline \textbf{{\textcolor{red}{Mg}}} & {\textcolor{red}{59.20 $\%$}} \\ \hline \textbf{Al micrometrico} & 36.20 $\%$ \\ \hline \textbf{{\textcolor{ForestGreen}{Al nanometrico}}} & {\textcolor{ForestGreen}{23.04 $\%$}} \\ \hline \textbf{$MgH_2$} & 33.65 $\%$ \\ \hline \textbf{Al nano + $MgH_2$} & 37.15 $\%$ \\ \hline \end{tabular}}

Any suggestion?

M