@@ -403,8 +403,12 @@ elementToHtml slideLevel opts (Sec level num (id',classes,keyvals) title' elemen
403403 then return mempty
404404 else do
405405 modify (\st -> st{ stElement = True})
406+ let level' = if level <= slideLevel &&
407+ slideVariant == SlidySlides
408+ then 1 -- see #3566
409+ else level
406410 res <- blockToHtml opts
407− (Header level (id',classes,keyvals) title')
411+ (Header level' (id',classes,keyvals) title')
408412 modify (\st -> st{ stElement = False})
409413 return res
410414