-\begin{tikzpicture}[node distance=1em,nodes={rectangle,draw,text=white,minimum width=10em,minimum height=2.5em}]
- \node (0) [fill=red] {Presentation layer};
- \node (1) [fill=violet,below=of 0] {Business layer};
- \node (2) [fill=blue,below=of 1] {Resource access layer};
+\begin{tikzpicture}[node distance=1em,nodes={rectangle,draw,minimum width=10em,minimum height=2.5em}]
+ \node (0) [fill=black!20,text=black] {Presentation};
+ \node (1) [fill=black!40,text=black,below=of 0] {Business};
+ \node (2) [fill=black!80,text=white,below=of 1] {Resource access};