页面末尾的 Tikz 行为

Question

我正在使用 tikz 将括号括起来作为所提到的枚举列表这里。我有两个带有多个注释的花括号，如下所示

问题是，当我的列表位于页面末尾时，我无法将括号放在正确的位置。括号出现在下一页的奇怪位置。有趣的是，如果我将列表移动到远离页面末尾的其他位置，我就会将其放在正确的位置。以下是代码

 \documentclass[sunil1]{sunil}

  \usepackage{lmodern,calc,tikz,textcomp}
  \usetikzlibrary{tikzmark,decorations.pathreplacing}
  \usetikzlibrary{calc}

\begin{document}
\newcommand\insm{%
  $\left.\rule{0pt}{1.6\baselineskip}\right\}$\parbox{\textwidth-2ex}{%
  \setlist[1]{itemsep=-5pt}
  \begin{itemize}
   \item[] (\textit{a} to \textit{b})
   \item[]Deformations 
   \item[] (\textit{b} to \textit{c})
  \end{itemize}}
 }    
\newcommand\wnsm{%
  $\left.\rule{0pt}{1.6\baselineskip}\right\}$\parbox{\textwidth-1ex}{%
  \setlist[1]{itemsep=-2pt}
  \begin{itemize}
   \item[] 
   \item[]Rigid-Body Motion
   \item[] (\textit{c} to \textit{d})
  \end{itemize}}
}

\begin{enumerate}
  \item A change in size (extension or contraction)\tikzmark{S}
  \item A change in shape (shear or distortion) \tikzmark{E}
  \item A rigid-body translation\tikzmark{W}
  \item A rigid-body rotation \tikzmark{N}
\end{enumerate}

 \tikz[remember picture, overlay]{%
   \node [shift={(1ex,.6ex)},text width=5.5cm,anchor=west] at ($(pic cs:S)!.5!(pic cs:E)$){\insm};}
 \tikz[remember picture, overlay]{%
   \node [shift={(1ex,.6ex)},text width=5.5cm,anchor=west] at ($(pic cs:W)!.5!(pic cs:N)$){\wnsm};}
\end{document}