--- a/slides.sty	Wed Nov 04 17:34:52 2020 +0000
+++ b/slides.sty	Sat Nov 07 00:07:28 2020 +0000
@@ -92,7 +92,10 @@
 
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\beamertemplateballitem
+% \beamertemplateballitem
+\setbeamertemplate{itemize item}[ball]
+\setbeamertemplate{itemize subitem}[ball]
+\setbeamertemplate{itemize subsubitem}[ball]
 \setlength\leftmargini{2mm}
 \setlength\leftmarginii{0.6cm}
 \setlength\leftmarginiii{1.5cm}