diff --git a/after/syntax/css/selectors-4.vim b/after/syntax/css/selectors-4.vim
index e22b43f..54e286b 100644
--- a/after/syntax/css/selectors-4.vim
+++ b/after/syntax/css/selectors-4.vim
@@ -1,3 +1,3 @@
 syn match cssSelectorOp "[|]"
-syn keyword cssPseudoClassId contained scope current past future default valid required optional blank playing paused any-link local-link read-only read-write placeholder-shown in-range out-of-range user-invalid user-valid target-within defined modal fullscreen picture-in-picture seeking buffering stalled muted volume-locked autofill
+syn keyword cssPseudoClassId contained scope current past future default valid required optional blank playing paused any-link local-link read-only read-write placeholder-shown in-range out-of-range user-invalid user-valid target-within defined modal fullscreen picture-in-picture seeking buffering stalled muted volume-locked autofill open closed
 syn region cssPseudoClassLang matchgroup=cssPseudoClassId start=":\(dir\|local-link\|current\|nth\(-last\)\=-col\|has\|where\)(" end=")" oneline
diff --git a/test/test.css b/test/test.css
index 40fc0d2..4cc44a4 100644
--- a/test/test.css
+++ b/test/test.css
@@ -877,7 +877,9 @@ mask {
 .selectors-4:muted,
 .selectors-4:volume-locked,
 .selectors-4:autofill,
-.selectors-4:user-valid {
+.selectors-4:user-valid,
+.selectors-4:open,
+.selectors-4:closed {
 	display: auto;
 }