# pgfplot axis title position

I would like to obtain the result that appear on the right (compiling the following MWE) by using title style:

\documentclass{standalone}
\usepackage{calc}
\usepackage{tikz}
\usetikzlibrary{calc,decorations,patterns,shapes.arrows}
\usepackage{mathtools}
\usepackage{tikzscale}
\usepackage{pgfplots}
\usepgfplotslibrary{groupplots,colormaps}pictures

\begin{document}

\begin{tikzpicture}
\begin{axis}[title=(a),
title style={at={(0,1)},
anchor=north west,
draw=black,fill=white}]
\end{axis}
\begin{axis}[xshift=10cm]
\node[draw=black,fill=white,anchor=north west] at (rel axis cs:0,1) {$(a)$};
\end{axis}
\end{tikzpicture}
\end{document}


A related (if not the same!) answered question is this one and suggests to use title style={at={(0.1,0.8)}}. I'd like to use, instead, something like title style={at={(0,1)},anchor=north west}, but as you can see, the result is not exactly what I want. Thank you

The problem is that title style does every axis title/.append style, while in the default title style there is yshift=6pt. Use every axis title/.style={..} instead of title style={..}, that will redefine the style completely.

\documentclass{standalone}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}

\begin{axis}[title=(a),every axis title/.style={below right,at={(0,1)},draw=black,fill=white}]