\DocumentMetadata{tagging = on, pdfstandard = ua-2}

\documentclass{ltx-talk}

\title{Footer colors}

\EditInstance{header}{std}{
  background-color = blue!50,
  color            = white,
}

\EditInstance{footer}{std}{
  background-color = blue!50
}

\begin{document}

\begin{frame}
  \frametitle{Frametitle}
  content
\end{frame}

\end{document}
