How can I make these arrow shades, for example to blue from white?
\documentclass{article}
\usepackage{chemfig}
\usepackage[version=3]{mhchem}
\begin{document}
\begin{figure}[!htb]
\centering
\scalebox{2}{
\schemestart
\chemfig{@{O1-2}\textcolor{gray}{O}=@{C1-2}\textbf{C}=@{O2-2}\textcolor{gray}{O}}
\schemestop
\chemmove{
\draw[blue][shorten <=3pt, shorten >=3pt](O1-2).. controls +(north:1cm) and +(120:1cm).. (C1-2);
\draw[blue][shorten <=3pt, shorten >=3pt](O2-2).. controls +(north:1cm) and +(60:1cm).. (C1-2);
}
}
\end{figure}
\end{document}