small change in slide with tikz tree that makes it compile

in Ubuntu 16.04 LTS.

tutorial04/slides/slides04.tex

@@ -300,7 +300,7 @@ $U = \bigl(V(\Omega_S)\bigr)^d \times P(\Omega_S) \times \Phi(\Omega_D)$
     \end{column}
     \begin{column}{0.4\textwidth}
 \begin{tikzpicture}
-    \scoped[every node/.style={draw=niceblue,fill=niceblue!20, text height=\heightof{$A_1$},text depth=\depthof{$A_1$},minimum width=.7cm}]
+    [every node/.style={draw=niceblue,fill=niceblue!20, minimum width=.7cm}]
   \node {$U$}
   child {
     node {TH}