How to create a rounded beamer block with the title starting a bit forward than the left margin?

Question

I've been trying to figure out what beamer template this presentation is in, but none of my tries (and searches) have come to a success. What I'm really interested in this template is actually the block types that they have used.

These blocks have rounded edges, and their titles don't start at the beginning of the left border, but a bit forward. Can you guys help me figure out what theme that is, or maybe how to replicate it?

Answer 1

For more options please see https://www.ctan.org/pkg/tcolorbox

\documentclass{beamer}
\usepackage[most]{tcolorbox}
\newtcolorbox{mybox}[2][]{%
    colback=bg, 
    colframe=blue!75!black,
    fonttitle=\bfseries,
    coltitle=blue!75!black, 
    colbacktitle=bg,
    enhanced,
    attach boxed title to top left={yshift=-1.2mm, xshift=2mm},
  title=#2,
  #1}
\begin{document}
\begin{frame}
\begin{mybox}{Hello there}
This is my own box with a mandatory title
and options.
\end{mybox}
\begin{mybox}[colframe=green!75!black,coltitle=green!75!black, ]{Hello there}
This is my own box with a mandatory title
and options.
\end{mybox}
\end{frame}
\end{document}

An alternative with the tcolorbox inner theme which will automatically get the colours from beamer's alert and example blocks:

\documentclass{beamer}
\useinnertheme[rounded]{tcolorbox}
\makeatletter
\tcbsetforeverylayer{
    boxrule=3pt,
    borderline={1pt}{0pt}{beamer@tcb@titlefg},
    attach boxed title to top left={yshift=-1.2mm, xshift=2mm},
}
\makeatother
\begin{document}
\begin{frame}
\begin{block}{Short title}
some text here
\end{block}
\begin{exampleblock}{A bit more long title}
some text here
\begin{alertblock}{ff}
dd
\end{alertblock}
\end{exampleblock}
\end{frame}
\end{document}