Remove backgroundcolor of title bar in Rochester Beamer Theme

Question

In the following minimal example, the title bar saying "Test frame" has a blue background:

\documentclass[compress, final]{beamer}
    \usetheme[height=0mm]{Rochester}
    \usecolortheme{dolphin}
    \useinnertheme{rectangles}
    \useoutertheme[footline=empty, subsection=true]{miniframes}

\begin{document}

\begin{frame}{Test frame}
    \begin{block}<+->{Block}
        Beamer is cool
    \end{block}
\end{frame}

\end{document}

In my opinion, it really makes the slide look "heavy". How can I remove the background color?

Answer 1

\setbeamercolor*{frametitle}{bg=white}

put it into the preamble before \begin{document}