# Alignment problem for enumerate within theorem with item of multiple lines

I'm a new TeX user and I met a problem recently when I was using an \enumerate environment inside my theorem environment. If an item extends to a second line or more, how can I remove the blank on the left while not affecting the position of the labels? (That can't be done by simply adjusting the leftmargin parameter, since it affects the labels.) Or, how can I align all lines of texts to the label in the left, as the red line in the following picture positioned? In addition, I've already tried \leavevmode, as advised in other questions, but that's not what I want.

Code here:

\documentclass{article}
\usepackage{amsthm}
\usepackage{enumitem}

\newtheorem{thm}{Theorem}[section]
\renewcommand{\labelenumi}{(\roman{enumi})}

\begin{document}
\section{A title here}
\begin{thm}
\begin{enumerate}
\item Long sentence. Really long sentence. Really really long sentence. Really.
\item Sentence presented here for comparison. creativity bull car nonsense filter choke smug
\end{enumerate}
\end{thm}
\end{document)
• Welcome to TeX SX! Please post a minimal code reproducing the problem. – Bernard Jul 19 '20 at 14:54
• Try to add \leavevmode after \begin{thm}. – ZhiyuanLck Jul 19 '20 at 15:29

Is it something like this you want? I thought that in the context of theorem, the enumeration looks better in upshape. If you want only the parentheses upshape, use label=$(\roman*)$.

\documentclass{article}
\usepackage{amsthm}
\usepackage{enumitem}

\newtheorem{thm}{Theorem}[section]
\setlist[enumerate, 1]{label=(\roman*)}

\begin{document}

\section{A title here}

\begin{thm}
\begin{enumerate}[font=\upshape, wide=0pt, labelsep=-0.3em, leftmargin =*]
\item Long sentence. Really long sentence. Really really long sentence. Really.
\item Sentence presented here for comparison. creativity bull car nonsense filter choke smug – Fiddle dee dee!
\end{enumerate}
\end{thm}

\end{docum

• Thanks! I tried your code and find it perfect! But I found one problem, that is, if I place the wide parameter after leftmargin, it would act differently and could solve my problem properly without adjusting labelsep. – HJ Zheng Jul 20 '20 at 2:21