将 pgfplot 的小网格移到大网格后面

Question

我注意到小网格y = const坐标线位于主网格坐标线之前。如何将小网格移到主网格后面？

\documentclass[tikz]{standalone}
\usepackage{pgfplots}

%===============================================================================
\begin{document}
\noindent
\begin{tikzpicture}
    ]
    \begin{axis}[
            grid = both,
            major grid style={line width=.3pt,draw=brown!75},
            minor tick num = 5,
            minor grid style = {line width=.1pt,draw=brown!10},
           xtick={-6,...,6}, % This one works now
        ]
        \addplot+[blue, no marks, domain={-6:6}] {x^2};
    \end{axis}
\end{tikzpicture}
\end{document}