diff --git a/package.json b/package.json
index 53fcab1..75f0122 100644
--- a/package.json
+++ b/package.json
@@ -5,7 +5,7 @@
     "format": "prettier . --check --write"
   },
   "dependencies": {
-    "@primer/css": "^15.2.0",
+    "@primer/css": "^21.2.0",
     "font-awesome": "^4.7.0",
     "jquery": "^3.5.1",
     "jquery.toc": "^0.4.0",