Specific indentation for enumerate item

Question

MWE:

\documentclass{beamer}

% Custom theme from https://bitbucket.org/marczellm/beamerports/src/30de28e687e2dfad6ebe0765d2eb622ed12fdbfe/beamerthemeKlope.sty?at=master
% It overwrites the default list style (see screenshot below)
\usepackage{../marczellm-beamerports-ad2150496d62/beamerthemeKlope}


\begin{document}
\begin{frame}
  \begin{enumerate}
    \item A
    \item B
    \item C
  \end{enumerate}
\end{frame}
\end{document}

I wish to change the indentation of item C. The closest result I achieved was by using \item \hspace{-4em}C. Obviously the number 3 has also to be moved to the left.

I also read about leftmargin in conjunction with itemize. Unfortunately, it does

a) not work with enumerate: \begin{enumerate}[leftmargin=-.5in] ("Something's wrong--perhaps a missing \item.")

b) and I don't see a way of assigning it to specific items. \item[leftmargin=-.5in] gives weird results.

---

@Steven B. Segletes' (now deleted) answer: I am actually using Beamer and a custom theme (this one). It seems that overridden styles are not taken into consideration with your code:

Answer 1

It is not clear to me why you would want to this, but anyway one technique is to adjust \itemindent. This will only work for the first line.

\documentclass{article}

\newlength{\stditemindent}
\makeatletter
\newcommand{\myitem}[1]{\setlength{\stditemindent}{\itemindent}%
\setlength{\itemindent}{-#1}\item\setlength{\itemindent}{\stditemindent}}
\makeatother

\usepackage{lipsum}

\begin{document}

\begin{enumerate}
  \item A
  \item B
  \myitem{2cm} C
  \item D
\end{enumerate}

\begin{enumerate}
  \item \lipsum[1]
  \item \lipsum[2]
  \myitem{2cm} \lipsum[3]
  \item \lipsum[4]
\end{enumerate}

\end{document}

In response to your first comment, the technique from the other question does work for enumerate, but as for itemize you have to load the enumitem package.