I tried to do a box with round corners and a title with tikz to do some definitions, properties,...

I tried this

```
\tikzset{mybox/.style={draw=black, thick,rectangle, rounded corners, inner sep=10pt, inner ysep=10pt}}
\tikzset{titlebox/.style={fill=white, text=black,thick,draw=black}}

\newcommand{\tikzboxb}[2]{%
\begin{tikzpicture}%
\node[mybox] (box){%
\begin{minipage}{0.96\linewidth}%
    #2%
\end{minipage} };%
\node[titlebox] at (box.north west) {%
    #1%
};%
\end{tikzpicture}%
}

\begin{document}

\tikzboxb{Propriété}{

\begin{center}
\begin{tikzpicture}[scale=0.3]
    \draw (0,0)--(8,1)--(4,5)--cycle;
\end{tikzpicture}
\end{center}

}

```

and even this 

```
\begin{tikzpicture}%
\begin{minipage}{0.96\linewidth}%
    \begin{tikzpicture}[scale=0.3]
        \draw (0,0)--(8,1)--(4,5)--cycle;
    \end{tikzpicture}
\end{minipage} };%
\node[fill=white, text=black,thick,draw=black , right=10pt] at (box.north west) {Propriété};%
\end{tikzpicture}

```

The result is 

[![enter image description here](https://i.stack.imgur.com/FrJxP.png)](https://i.stack.imgur.com/FrJxP.png)

In both case there is a problem. In the first case, the box doesn't look like I want which is the case with the second test.

In both case the triangle s have round corners !

It seems that the style I defined for the node (and only for It) was used for all the drawings.

I tried so many changes that I am exhausted and I need some help.

Thanks, Benoît