Enumeration indentation

Question

I don't know, how this enumeration should be indented. It gives me the enumeration closely next to the word "Practice" and it should be on the separate line (under "Practice").

\documentclass[a4paper, 10pt]{article}
\usepackage{czech,amsmath,amsthm,amsfonts,multicol}
\topmargin0pt
\headheight0pt
\headsep0pt
\oddsidemargin0pt
\evensidemargin0pt
\setlength{\textwidth}{\paperwidth}
\addtolength{\textwidth}{-2in}
\setlength{\textheight}{\paperheight}
\addtolength{\textheight}{-2in}

\begin{document}
\theoremstyle{remark}
\newtheorem*{practice}{Practice}

\renewcommand{\labelenumi}{[\arabic{enumi}]}
\renewcommand{\labelenumii}{(\roman{enumii})}

\begin{practice}

\begin{enumerate}
    \item ccc
    \begin{enumerate}
        \item fff
        \item fff
    \end{enumerate}
    \item fff
\end{practice}
\end{document}