tcolor 不能锐角

Question

\documentclass [12pt,a4paper]{jarticle}
\usepackage[italian]{babel}
\usepackage[dvipdfmx]{graphicx}
\usepackage[utf8]{inputenc}
\usepackage{ascmac}
\usepackage{tcolorbox}
\tcbuselibrary{skins} %preamble


% --------------------
\begin{document}
\begin{tcolorbox}
    [   colframe    =   blue,
        colback =   white,
        colbacktitle    =   red!40!white,
        coltitle    =   black,  fonttitle   =   \bfseries,
         title      =   My box,
        sharpish corners
        ]
box contents
\end{tcolorbox}




% --------------------
\end{document}

日志

Package pgfkeys Error: I do not know the key '/tcb/sharp corners' and I am
 going to ignore it. Perhaps you misspelled it.

See the pgfkeys package documentation for explanation.
Type  H <return>  for immediate help.

为什么？

Answer 1

这是否满足

平均能量损失

\documentclass [12pt,a4paper]{article}% changed from jarticle to article
\usepackage[italian]{babel}
\usepackage{graphicx}
\usepackage[utf8]{inputenc}
\usepackage{ascmac}
\usepackage{tcolorbox}
\tcbuselibrary{skins} %preamble


% --------------------
\begin{document}

    \newtcolorbox{twotitle}{%
        colframe=blue,
        colback=white,
        colbacktitle=red!40!white,
        coltitle=black,  
        fonttitle=\bfseries,
        title=My box,
        sharpish corners
    }
        \begin{twotitle}
        box contents
        \end{twotitle}


\end{document}