\begin{figure}[tb]
\small
%\begin{center}
\begin{tikzpicture}[scale=0.6]
\node [inner sep=0pt] (a1) {US};
\node [inner sep=0pt, left of = a1, node distance = 3.4em] (a0) {};

\node [inner sep=0pt, right of = a1, node distance = 2.2em] (a2) {and};
\node [inner sep=0pt, right of = a2, node distance = 2.2em] (a3) {UK};
\node [compose, black, fill = pink!80, opacity=.8, right of = a3, minimum height = 1.5em,  minimum width = 3.5em, inner sep=1pt,  node distance = 3.5em]   (a4){Criticise};
%\node [inner sep=0pt, right of = a3, node distance = 3.5em] (a4) {Criticise};
\node [inner sep=0pt, right of = a4, node distance = 4.2em] (a5) {Mugabe};
\node [inner sep=0pt, right of = a5, node distance = 2.8em] (a6) {'s};
\node [inner sep=0pt, right of = a6, node distance = 2.5em] (a7) {Victory};

%gold ref
\node[above of = a0, node distance = 1.5em] (gold) {Gold};
\node [right of = a1, node distance = 2.3em] (a1-a3-m) {};
\node [compose, black, fill = a2czy, opacity=.8, above of = a1-a3-m, minimum height = 1.5em,  minimum width = 7em, inner sep=0pt,  node distance = 1.5em]   (span-a1a3){Holder};
%\node [compose, black, fill = pink!80, opacity=.8, above of = a4, minimum height = 1.5em,  minimum width = 3.2em, inner sep=0pt,  node distance = 1.5em]   (span-a4){DSE};
\node [compose, black, fill = green!50, opacity=.8, above of = a6, minimum height = 1.5em,  minimum width = 8.0em, inner sep=0pt,  node distance = 1.5em]   (){Target};

%base ref
\node[below of = a0, node distance = 1.5em] (base) {Base};
%\node [compose, black, fill = pink!80, opacity=.8, below of = a4, minimum height = 1.5em,  minimum width = 3.2em, inner sep=0pt,  node distance = 1.7em]   (span-a4){DSE};
\node [compose, black, fill = green!45, opacity=.8, below of = a6, minimum height = 1.5em,  minimum width = 8.0em, inner sep=0pt,  node distance = 1.7em]   (span-a4){Target};

%bert
\node[below of = base, node distance = 1.9em] (bert) {+BERT};
\node [compose, black, fill = a2czy, opacity=.8, below of = a3, minimum height = 1.5em,  minimum width = 1.5em, inner sep=1pt,  node distance = 3.7em]   (){Holder};
%\node [compose, black, fill = pink!80, opacity=.8, below of = a4, minimum height = 1.5em,  minimum width = 3.2em, inner sep=0pt,  node distance = 3.7em]   (span-a4){DSE};
\node [compose, black, fill = green!45, opacity=.8, below of = a6, minimum height = 1.5em,  minimum width = 8.0em, inner sep=0pt,  node distance = 3.7em]   (){Target};

%syntax
\node[below of = bert, node distance = 2.1em] (syntax) {+Syntax};
\node [compose, black, fill = a2czy, opacity=.8, below of = a1-a3-m, minimum height = 1.5em,  minimum width = 7em, inner sep=0pt,  node distance = 5.5em]   (span-a1a3){Holder};
%\node [compose, black, fill = pink!80, opacity=.8, below of = a4, minimum height = 1.5em,  minimum width = 3.2em, inner sep=0pt,  node distance = 5.5em]   (span-a4){DSE};
\node [compose, black, fill = green!45, opacity=.8, below of = a6, minimum height = 1.5em,  minimum width = 8.0em, inner sep=0pt,  node distance = 5.5em]   (){Target};

\end{tikzpicture}
%\end{center}
\caption{An example of different ORL outputs for ``US and UK Criticise Mugabe 's Victory".}
\label{fig:case_study}
\end{figure}
