diff --git a/Userland/Libraries/LibWeb/CSS/Properties.json b/Userland/Libraries/LibWeb/CSS/Properties.json
index f3e0e947fc..ec9b10ce8d 100644
--- a/Userland/Libraries/LibWeb/CSS/Properties.json
+++ b/Userland/Libraries/LibWeb/CSS/Properties.json
@@ -829,7 +829,8 @@
     "inherited": true,
     "initial": "normal",
     "valid-types": [
-      "length"
+      "length",
+      "percentage"
     ],
     "valid-identifiers": [
       "normal"
@@ -1459,7 +1460,8 @@
     "inherited": true,
     "initial": "normal",
     "valid-types": [
-      "length"
+      "length",
+      "percentage"
     ],
     "valid-identifiers": [
       "normal"