move down the header setting which was being reset by \metroset

slides_template/example.tex

@@ -10,15 +10,6 @@
 \usepackage{tagpdf}
 \tagpdfsetup{activate-all}
 
-% Tag frame titles as H1 headings for PDF accessibility
-\addtobeamertemplate{frametitle}{%
-  \tagstructbegin{tag=H1}%
-  \tagmcbegin{tag=H1}%
-}{%
-  \tagmcend%
-  \tagstructend%
-}
-
 \usepackage{pgfpages}
 \input{notes.config}
 
@@ -35,6 +26,16 @@
 \metroset{block=fill}
 % \metroset{background=light}
 
+% Tag frame titles as H1 headings for PDF accessibility
+% (must come after all \metroset calls, which reset the frametitle template)
+\addtobeamertemplate{frametitle}{%
+  \tagstructbegin{tag=H1}%
+  \tagmcbegin{tag=H1}%
+}{%
+  \tagmcend%
+  \tagstructend%
+}
+
 \setsansfont{OpenSans}[
 Path = ./fonts/OpenSans/,
 Extension = .ttf,