diff --git a/docs/package.json b/docs/package.json
index 70a56d7..b338abf 100644
--- a/docs/package.json
+++ b/docs/package.json
@@ -39,7 +39,7 @@
   },
   "devDependencies": {
     "@rollup/plugin-terser": "^1.0.0",
-    "cssnano": "^8.0.2",
+    "cssnano": "^9.0.1",
     "grunt": "^1.6.1",
     "grunt-contrib-clean": "^2.0.1",
     "grunt-contrib-copy": "^1.0.0",