Partially transparent text box

Question

I am trying to make a poster using beamer. Can any one please reply me, my question is:

How can I make my boxes partially transparent so that my background will be visible through the boxes?

Answer 1

The following was taken verbatim from the PGF documentation (section 20 Transparency, p 234):

\documentclass{article}
\usepackage{tikz}% http://ctan.org/pkg/tikz
\begin{document}
\begin{tikzpicture}[every node/.style={fill,draw}]
  \draw[line width=2mm,blue!50,line cap=round] (0,0) grid (3,2);
  \node[opacity=0.5] at (1.5,2) {Upper node};
  \node[draw opacity=0.8,fill opacity=0.2,text opacity=1]
    at (1.5,0) {Lower node};
\end{tikzpicture}
\end{document}

It translates directly to beamer.