diff --git a/.marp/Makefile b/.marp/Makefile
index 3d851cf..04b1725 100644
--- a/.marp/Makefile
+++ b/.marp/Makefile
@@ -5,7 +5,7 @@ build: theme.css
 
 %.css: %.scss
 	cd .. \
-		&& npx sass --no-error-css --no-source-map .marp/$<:.marp/$@ \
+		&& npx sass --no-error-css --no-source-map --style=expanded .marp/$<:.marp/$@ \
 		|| ( rm -f .marp/$@ && exit 1 )
 
 .PHONY: build