diff --git a/ed/csspatches/css-values-5.json.patch b/ed/csspatches/css-values-5.json.patch
deleted file mode 100644
index af2a9d69645d..000000000000
--- a/ed/csspatches/css-values-5.json.patch
+++ /dev/null
@@ -1,42 +0,0 @@
-From 8c563b373f70cd3fce87fdb457e429d88797aba0 Mon Sep 17 00:00:00 2001
-From: Francois Daoust <fd@tidoust.net>
-Date: Wed, 13 Nov 2024 10:17:40 +0100
-Subject: [PATCH] Amend syntax of `if()`, drop value of `<if-condition>`
-
-For `if()`, parsing fails on `;?`.
-
-For `<if-condition>`, the problem is that the spec extends the Value Definition
-Syntax with a new construct that is not yet supported by the CSS parser.
-
-Both problems have been fixed in CSSTree already, but a new version still needs
-to be released and the CSS WG changed the syntax of the boolean expression
-multiplier. See tracking issues in:
-https://github.com/w3c/webref/issues/1378
-https://github.com/csstree/csstree/issues/307
----
- ed/css/css-values-5.json | 5 ++---
- 1 file changed, 2 insertions(+), 3 deletions(-)
-
-diff --git a/ed/css/css-values-5.json b/ed/css/css-values-5.json
-index 62386d10e..9f2b6c925 100644
---- a/ed/css/css-values-5.json
-+++ b/ed/css/css-values-5.json
-@@ -468,13 +468,12 @@
-       "name": "<if()>",
-       "href": "https://drafts.csswg.org/css-values-5/#typedef-if",
-       "type": "type",
--      "value": "if( [ <if-condition> : <declaration-value>? ; ]* <if-condition> : <declaration-value>? ;? )"
-+      "value": "if( [ <if-condition> : <declaration-value>? ; ]* <if-condition> : <declaration-value>? ';'? )"
-     },
-     {
-       "name": "<if-condition>",
-       "href": "https://drafts.csswg.org/css-values-5/#typedef-if-condition",
--      "type": "type",
--      "value": "<boolean-expr[ <if-test> ]> | else"
-+      "type": "type"
-     },
-     {
-       "name": "<if-test>",
--- 
-2.37.1.windows.1
-
diff --git a/package-lock.json b/package-lock.json
index e290661a6dc4..6e8886dfd848 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -17,7 +17,7 @@
         "@webref/elements": "file:packages/elements",
         "@webref/events": "file:packages/events",
         "@webref/idl": "file:packages/idl",
-        "css-tree": "2.3.1",
+        "css-tree": "^3.1.0",
         "flags": "0.2.2",
         "mocha": "11.0.1",
         "reffy": "18.0.0",
@@ -1098,12 +1098,13 @@
       }
     },
     "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",
       "dependencies": {
-        "mdn-data": "2.0.30",
+        "mdn-data": "2.12.2",
         "source-map-js": "^1.0.1"
       },
       "engines": {
@@ -2147,10 +2148,11 @@
       }
     },
     "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==",
-      "dev": true
+      "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"
     },
     "node_modules/mime-db": {
       "version": "1.52.0",
@@ -3706,7 +3708,7 @@
       "dev": true,
       "license": "MIT",
       "peerDependencies": {
-        "css-tree": "^2.3.1"
+        "css-tree": "^3.1.0"
       }
     },
     "packages/elements": {
@@ -4541,12 +4543,12 @@
       }
     },
     "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,
       "requires": {
-        "mdn-data": "2.0.30",
+        "mdn-data": "2.12.2",
         "source-map-js": "^1.0.1"
       }
     },
@@ -5300,9 +5302,9 @@
       }
     },
     "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
     },
     "mime-db": {
diff --git a/package.json b/package.json
index d500a5f377b2..835d93c5f005 100644
--- a/package.json
+++ b/package.json
@@ -33,7 +33,7 @@
     "@webref/elements": "file:packages/elements",
     "@webref/events": "file:packages/events",
     "@webref/idl": "file:packages/idl",
-    "css-tree": "2.3.1",
+    "css-tree": "3.1.0",
     "flags": "0.2.2",
     "mocha": "11.0.1",
     "reffy": "18.0.0",
diff --git a/packages/css/package.json b/packages/css/package.json
index 559f436e30b0..af90f5a6440e 100644
--- a/packages/css/package.json
+++ b/packages/css/package.json
@@ -12,6 +12,6 @@
   "license": "MIT",
   "main": "index.js",
   "peerDependencies": {
-    "css-tree": "^2.3.1"
+    "css-tree": "^3.1.0"
   }
 }
\ No newline at end of file