Frage zu angle, voller Winkel

\documentclass[headheight=19pt]{scrartcl}
%------------------------------------------------------------------------------
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage[ngerman]{babel}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage[norndcorners,customcolors,nofill]{hf-tikz} 
\usepackage{tikz}
\usetikzlibrary{angles,quotes,intersections}
\tikzset{
  angle radius=0.75cm
}
\usetikzlibrary{quotes,babel,angles}
%------------------------------------------------------------------------------
\newbox\mytikzbox 
\newcommand{\tikzBox}[2][\mytikzbox]{% 
   \sbox#1{\pgfinterruptpicture#2\endpgfinterruptpicture}}
%-------------------------------------------------------------------------------
\tikzstyle{mybox}=[draw=gray, fill=white!20, align=left,  text width = 0.9\linewidth]
\hfsetbordercolor{gray}

\tikzset{
  winkel/.style={draw=gray,angle eccentricity=.6,angle radius=1cm},
  mybox/.style={draw=gray,fill=white,align=left,text width=.9\linewidth}
}
%-------------------------------------------------------------------------------
\begin{document}
\begin{tikzpicture}
  \coordinate[label=below:S] (S) at (0,0);
  \draw[name path=A] (0,0) coordinate (A) -- (2,0) coordinate (B);
  \draw[name path=B] (0,0) coordinate (C) -- (0,2) coordinate (D);
  %\path[name intersections={of=A and B,name=i}];
  \draw pic["$\alpha$", draw=gray, -] {angle=B--S--C};
  \fill (S) circle (1pt);
  %\draw pic["$\beta$", draw=blue, ->] {angle=C--i-1--A};
\end{tikzpicture}
\end{document}