diff --git a/css/css-scoping/slotted-details-content-ref.html b/css/css-scoping/slotted-details-content-ref.html
new file mode 100644
index 00000000000000..f99ca29497753a
--- /dev/null
+++ b/css/css-scoping/slotted-details-content-ref.html
@@ -0,0 +1,3 @@
+
+
+This text should be green
diff --git a/css/css-scoping/slotted-details-content.html b/css/css-scoping/slotted-details-content.html
new file mode 100644
index 00000000000000..005098bd2544a6
--- /dev/null
+++ b/css/css-scoping/slotted-details-content.html
@@ -0,0 +1,17 @@
+
+
+CSS Scoping Test: ::slotted() allows ::details-content
+
+
+
+
+ This text should be green
+
+
diff --git a/css/css-scoping/slotted-parsing.html b/css/css-scoping/slotted-parsing.html
index e4657b588af5e0..9fc71d32f4fea7 100644
--- a/css/css-scoping/slotted-parsing.html
+++ b/css/css-scoping/slotted-parsing.html
@@ -39,6 +39,7 @@
// Allow tree-abiding pseudo elements after ::slotted
test_valid_selector("::slotted(*)::before");
test_valid_selector("::slotted(*)::after");
+ test_valid_selector("::slotted(*)::details-content");
test_valid_selector("::slotted(*)::placeholder");
test_valid_selector("::slotted(*)::marker");