fix: switch to recent version of sass

.marp/Makefile

@@ -5,8 +5,10 @@ build: theme.css
 
 %.css: %.scss
 	cd .. \
-		&& npx node-sass --output-style compressed .marp/$< > .marp/$@ \
+		&& npx sass --no-error-css --no-source-map .marp/$<:.marp/$@ \
 		|| ( rm -f .marp/$@ && exit 1 )
 
 .PHONY: build
 
+clean:
+	rm -f theme.css

package.json

@@ -12,11 +12,11 @@
   "author": "",
   "license": "ISC",
   "dependencies": {
-    "@marp-team/marp-cli": "^3.4.0",
+    "@marp-team/marp-cli": "^1.4.1",
     "@marp-team/marp-core": "^3.9.0",
     "foreman": "^3.0.1",
     "markdown-it-footnote": "^3.0.2",
     "markdown-it-highlight-lines": "^1.0.2",
-    "node-sass": "^7.0.0"
+    "sass": "^1.79.3"
   }
 }