Draw a colorful note box in tcolorbox

tcolorbox

I would like to make a note box where I can place key ideas for my students.
I have these codes as MWE

\documentclass[openany]{book} 
\usepackage[many]{tcolorbox} 
\newtcolorbox{mynote}{% 
enhanced, left=1cm, breakable, 
colback=yellow!20, colbacktitle=yellow!20, colframe=yellow!20, 
sharp corners, 
width=90mm, 
fonttitle=\Large\bfseries, 
title=\textcolor{green!70!black}{Note}, 
overlay={\draw[dashed,line width=2pt,green!70!black] ([yshift=5pt,xshift=1.2cm]frame.west)--([yshift=5pt]frame.east);}, drop fuzzy shadow=gray!50 } 

\begin{document} 
\begin{mynote} 
The letter I is often used for the point (1,0). 
\end{mynote} 
\end{document}

When I compiled, this was the result:
enter image description here

But what I need is as below:

enter image description here

Thanks in advance for any kind help from the community

Best Answer

enter image description here

\documentclass[openany]{book} 
\usepackage[many]{tcolorbox} 
\newtcolorbox{mynote}{% 
enhanced, left=1cm, breakable, 
colback=yellow!20, colbacktitle=yellow!20, colframe=yellow!20, 
sharp corners, 
width=90mm, 
fonttitle=\Large\bfseries, 
title=\textcolor{green!70!black}{Note}, 
overlay={\draw[dashed,line width=2pt,green!70!black] ([yshift=5pt,xshift=1.2cm]frame.west)--([yshift=5pt]frame.east);
\fill[green!70!black](frame.north west)--++(-90:4mm)--++(-45:3mm)--++(45:3mm)|-cycle;}, drop fuzzy shadow=gray!50 } 

\begin{document} 
\begin{mynote} 
The letter I is often used for the point (1,0). 
\end{mynote} 
\end{document}
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