\tikzset{
  parallel/.style={
    minimum width=4.3cm,
    minimum height=1cm,
    align=center,
    draw=none,
    preaction={
      draw,
      fill=green!10,
      fill opacity=1,
      path picture={
        \begin{scope}[shift={(0.2cm,-0.2cm)}]
          \draw[fill=green!10,draw=black] 
            (path picture bounding box.south west) rectangle 
            (path picture bounding box.north east);
        \end{scope}
        \begin{scope}[shift={(0.1cm,-0.1cm)}]
          \draw[fill=green!10,draw=black]
            (path picture bounding box.south west) rectangle 
            (path picture bounding box.north east);
        \end{scope}
      }
    },
    draw=black,
    fill=green!10
  }
}
