how can I make that the shaded part is a little lighter than the rest?

Question

I want to draw one figure as follows

but how can I make that the shaded part what I marked in red is a little lighter than the rest? or use dashed line for that part?

my MWE is as follows

\begin{tikzpicture}
  \draw (-4,0) -- (4,0);
  \draw (0,-5) -- (0,5);
  \fill (0,0) coordinate (o) node[anchor=north east]{$O$};
\draw[fill=Green,opacity=0.3,] (1,2.5) -- (1,-1.5) node[text=black,opacity=1,below,xshift=-0.5cm,yshift=-0.5cm]{$W$}-- (-1,-2.5) -- (-1,1.5) -- cycle;
  \draw[mydarkblue, line width=1pt] (3,-1.5) node[above,text=black]{$L$} -- (-2,1);
\end{tikzpicture}

Thanks in advance.

Answer 1

What I changed:

• Draw the line segment behind plane, then the plane, then the line segment in front of plane. (You may want to do similar things to the horizontal axis line.)
• Fill the plane in light green fill=Green!30 and adjust the opacity opacity=.8.

\documentclass{article}
\usepackage[svgnames]{xcolor}
\usepackage{tikz}
\colorlet{mydarkblue}{blue!50!black}
\begin{document}
\begin{tikzpicture}
  \draw (-4,0) -- (4,0);
  \draw (0,-5) -- (0,5);
  \fill (0,0) coordinate (o) node[anchor=north east]{$O$};
\draw[mydarkblue, line width=1pt] (-2,1) -- (0,0);
  \draw[fill=Green!30, opacity=.8] 
    (1,2.5) -- (1,-1.5)
      node[text=black, opacity=1, below, xshift=-0.5cm, yshift=-0.5cm] {$W$}
    -- (-1,-2.5) -- (-1,1.5) -- cycle;
  \draw[mydarkblue, line width=1pt] (3,-1.5) node[above,text=black] {$L$} -- (0,0);
\end{tikzpicture}
\end{document}