diff --git a/package-lock.json b/package-lock.json
index 37a1c1b..04f545d 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -13,7 +13,7 @@
         "@types/chai": "^5.2.2",
         "@types/mocha": "^10.0.10",
         "@types/node": "22",
-        "@webref/css": "~6.16.1",
+        "@webref/css": "~7.1.3",
         "chai": "^6.2.0",
         "dedent-js": "^1.0.1",
         "eslint": "^9.37.0",
@@ -654,13 +654,13 @@
       }
     },
     "node_modules/@webref/css": {
-      "version": "6.16.1",
-      "resolved": "https://registry.npmjs.org/@webref/css/-/css-6.16.1.tgz",
-      "integrity": "sha512-35QpBnNHloWvNmHU4aHH36/40z7RhJf19dgeqr/O0jtbN0plg5xPmlE6MRxdSYItjb1ffh/AM4mA/hpud2E4Nw==",
+      "version": "7.1.3",
+      "resolved": "https://registry.npmjs.org/@webref/css/-/css-7.1.3.tgz",
+      "integrity": "sha512-D/RgB1PFwkwHlcpAUehXnZ30ZU7cIo/9lBZEF4N9xQFhMwqemkSV7wj8Ygebr3Q/Zo0qsAzwxuvz2roW4n+QGg==",
       "dev": true,
       "license": "MIT",
       "peerDependencies": {
-        "css-tree": "^2.3.1"
+        "css-tree": "^3.1.0"
       }
     },
     "node_modules/acorn": {
@@ -964,14 +964,14 @@
       }
     },
     "node_modules/css-tree": {
-      "version": "2.3.1",
-      "resolved": "https://registry.npmjs.org/css-tree/-/css-tree-2.3.1.tgz",
-      "integrity": "sha512-6Fv1DV/TYw//QF5IzQdqsNDjx/wc8TrMBZsqjL9eW01tWb7R7k/mq+/VXfJCl7SoD5emsJop9cOByJZfs8hYIw==",
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/css-tree/-/css-tree-3.1.0.tgz",
+      "integrity": "sha512-0eW44TGN5SQXU1mWSkKwFstI/22X2bG1nYzZTYMAWjylYURhse752YgbE4Cx46AC+bAvI+/dYTPRk1LqSUnu6w==",
       "dev": true,
       "license": "MIT",
       "peer": true,
       "dependencies": {
-        "mdn-data": "2.0.30",
+        "mdn-data": "2.12.2",
         "source-map-js": "^1.0.1"
       },
       "engines": {
@@ -1755,9 +1755,9 @@
       "license": "ISC"
     },
     "node_modules/mdn-data": {
-      "version": "2.0.30",
-      "resolved": "https://registry.npmjs.org/mdn-data/-/mdn-data-2.0.30.tgz",
-      "integrity": "sha512-GaqWWShW4kv/G9IEucWScBx9G1/vsFZZJUO+tD26M8J8z3Kw5RDQjaoZe03YAClgeS/SWPOcb4nkFBTEi5DUEA==",
+      "version": "2.12.2",
+      "resolved": "https://registry.npmjs.org/mdn-data/-/mdn-data-2.12.2.tgz",
+      "integrity": "sha512-IEn+pegP1aManZuckezWCO+XZQDplx1366JoVhTpMpBB1sPey/SbveZQUosKiKiGYjg1wH4pMlNgXbCiYgihQA==",
       "dev": true,
       "license": "CC0-1.0",
       "peer": true
diff --git a/package.json b/package.json
index 1d7fa28..62497c6 100644
--- a/package.json
+++ b/package.json
@@ -19,7 +19,7 @@
     "@types/chai": "^5.2.2",
     "@types/mocha": "^10.0.10",
     "@types/node": "22",
-    "@webref/css": "~6.16.1",
+    "@webref/css": "~7.1.3",
     "chai": "^6.2.0",
     "dedent-js": "^1.0.1",
     "eslint": "^9.37.0",