diff --git a/submodules/Makefile b/submodules/Makefile
index f17068a..0a1ddd8 100644
--- a/submodules/Makefile
+++ b/submodules/Makefile
@@ -21,3 +21,8 @@ buildMaterialize: updateSubmodules
 deployMaterialize: buildMaterialize
 	# @todo correctly check the cert
 	lftp -e "set ftp:ssl-allow no; mirror -R 'materialize/dist' 'www/ressourcen/materializeCss'; bye;" -u cwsvjudo,$(ftpPassword) cwsvjudo.bplaced.net
+
+.PHONY: clean
+clean:
+	git submodule foreach git clean -xdf
+	git submodule foreach git restore .
diff --git a/submodules/lite-youtube-embed b/submodules/lite-youtube-embed
index 217b3cd..8728048 160000
--- a/submodules/lite-youtube-embed
+++ b/submodules/lite-youtube-embed
@@ -1 +1 @@
-Subproject commit 217b3cde1aa44ab943c99fc17b4cca7d6b3613f3
+Subproject commit 8728048ebe264300140d22c5300761610f6834ba
diff --git a/submodules/materialize b/submodules/materialize
index 93e673c..dda2c95 160000
--- a/submodules/materialize
+++ b/submodules/materialize
@@ -1 +1 @@
-Subproject commit 93e673c19fd6e1dee2b1dc77ac0e7c95fd39fbe9
+Subproject commit dda2c95aee0cadbba52c1cb726214d6ef8131e8b
diff --git a/submodules/parsedown b/submodules/parsedown
index 1ff0382..999fcf7 160000
--- a/submodules/parsedown
+++ b/submodules/parsedown
@@ -1 +1 @@
-Subproject commit 1ff038273949df7d6a455352659a878f3c89b29c
+Subproject commit 999fcf788675b65b5344e2744443fc4d5f76cc14
diff --git a/submodules/zopfli b/submodules/zopfli
index 831773b..ccf9f05 160000
--- a/submodules/zopfli
+++ b/submodules/zopfli
@@ -1 +1 @@
-Subproject commit 831773bc28e318b91a3255fa12c9fcde1606058b
+Subproject commit ccf9f0588d4a4509cb1040310ec122243e670ee6