diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index d5f6451c..9a449602 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "3.6.5"
+  ".": "3.6.6"
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 80fe0f40..b3a81551 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## [3.6.6](https://github.com/eslint/csstree/compare/css-tree-v3.6.5...css-tree-v3.6.6) (2025-10-02)
+
+
+### Bug Fixes
+
+* add support for relative color values ([#87](https://github.com/eslint/csstree/issues/87)) ([486c559](https://github.com/eslint/csstree/commit/486c559ff4e9bed5c8f8b31f08396ca0737c8f78))
+* allow relative color syntax for rgb() & rgba() ([#80](https://github.com/eslint/csstree/issues/80)) ([a08c7ab](https://github.com/eslint/csstree/commit/a08c7ab7496ac653fc1c510d99e67d633a5f3139))
+
 ## [3.6.5](https://github.com/eslint/csstree/compare/css-tree-v3.6.4...css-tree-v3.6.5) (2025-08-25)
 
 
diff --git a/package-lock.json b/package-lock.json
index f80609c8..ee73fda7 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@eslint/css-tree",
-  "version": "3.6.5",
+  "version": "3.6.6",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "@eslint/css-tree",
-      "version": "3.6.5",
+      "version": "3.6.6",
       "license": "MIT",
       "dependencies": {
         "mdn-data": "2.23.0",
diff --git a/package.json b/package.json
index 654fb3f4..2be96a44 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@eslint/css-tree",
-  "version": "3.6.5",
+  "version": "3.6.6",
   "description": "A tool set for CSS: fast detailed parser (CSS → AST), walker (AST traversal), generator (AST → CSS) and lexer (validation and matching) based on specs and browser implementations",
   "author": "Roman Dvornov <rdvornov@gmail.com> (https://github.com/lahmatiy)",
   "license": "MIT",