# Different colors in title page and frame title with Focus Beamer theme

I'm using the Focus theme for Beamer, and I'd like to have a custom background color for the title page (+ the section pages), and a different color in the headers and footers of individual slides: say a nice dark red for the title page, and a more neutral grey for the slides.

I am able to change the color of the footer, but not the header, see code below. I would expect something like \setbeamercolor{frametitle} or \setbeamercolor{headline} would do the trick, but the former changes colors everywhere (i.e., also on the title page) while the latter does nothing.

Any tips short of going into the .sty files?

\documentclass{beamer}
\usetheme{focus}
\definecolor{main}{RGB}{141, 2, 31} % dark red
\setbeamercolor{footline}{bg=black!60}
% \setbeamercolor{frametitle}{bg=black!60}

\title{Title Page}

\begin{document}
\begin{frame}
\maketitle
\end{frame}

\begin{frame}{Frame}
Hello!
\end{frame}
\end{document}


Produces this:

Unfortunately the focus theme does not provide any tools to change these colours independently, so one needs to resort to a bit of violence against the theme:

% !TeX TS-program = lualatex

\documentclass{beamer}
\usetheme{focus}
\definecolor{main}{RGB}{141, 2, 31} % dark red
\setbeamercolor{footline}{bg=black!60}
% \setbeamercolor{frametitle}{bg=black!60}

\setbeamercolor{mycolor}{bg=blue}
\makeatletter
\let\beamer@@tmpop@frametitle@focus\undefined
\defbeamertemplate*{frametitle}{focus}{%
% If not title page.
\vspace{-1pt}%
\begin{beamercolorbox}[wd=\paperwidth,leftskip=0.55cm,rightskip=0.55cm,sep=0.2cm]{mycolor}%
\strut\insertframetitle\strut%
\end{beamercolorbox}%
\fi%
}

\makeatother

\title{Title Page}

\begin{document}
\begin{frame}
\maketitle
\end{frame}

\begin{frame}{Frame}
Hello!
\end{frame}

\section{section}

\begin{frame}
\frametitle{title}
content...
\end{frame}
\end{document}