ui: clean with makefile

ui/Makefile

@@ -5,10 +5,13 @@ watch:
 	sass styles:static --watch
 
 dist:
+	@echo clean dist
+	@rm -rf dist/index.html
+	@rm -rf dist/static
 	@echo "compile styles/*.scss"
 	@sass styles/base.scss static/base.css
 	@ruby scripts/compile.rb
-	cp -R ./static dist/static
+	cp -R ./static dist/static/
 	cp index.html dist/index.html
 
 .PHONY: server watch dist