I want to change colors for various elements in a presentation with Frankfurt style. I found how to change background and text color in the frametitle and outline ribbon, but I get two pale, horizontal green lines over and under the frame title. Any idea how I could remove them?
\documentclass[xcolor=dvipsnames]{beamer}
\usetheme{Frankfurt}
\beamertemplatenavigationsymbolsempty
\setbeamercolor{section in head/foot}{fg=OliveGreen!40!Sepia, bg=OliveGreen!70!YellowGreen}
\setbeamercolor{structure}{fg=LimeGreen, bg = LimeGreen}
\setbeamercolor{alerted text}{fg=LimeGreen}
\setbeamercolor{title}{fg=Sepia, bg = LimeGreen!60!GreenYellow}
\setbeamercolor{frametitle}{fg=OliveGreen!60!Sepia, bg = LimeGreen!60!GreenYellow}
\title{Title}
\author{Me}
\date{Today}
\begin{document}
\section[My first section]{Section 1}
\begin{frame}
\frametitle{Frame title}
Some text
\end{frame}
\end{document}
This gives (red arrows added manually) :