diff --git a/e2e/package-lock.json b/e2e/package-lock.json
index 2859c4b286..50b4bd5550 100644
--- a/e2e/package-lock.json
+++ b/e2e/package-lock.json
@@ -107,7 +107,7 @@
 				"@csstools/pack-test": "*",
 				"@csstools/postcss-bundler": "*",
 				"@csstools/postcss-tape": "*",
-				"@webref/css": "8.5.0"
+				"@webref/css": "8.5.1"
 			},
 			"engines": {
 				"node": ">=20.19.0"
@@ -583,7 +583,6 @@
 			"resolved": "https://registry.npmjs.org/acorn/-/acorn-8.16.0.tgz",
 			"integrity": "sha512-UVJyE9MttOsBQIDKw1skb9nAwQuR5wuGD3+82K6JgJlm/Y+KI92oNsMNGZCYdDsVtRHSak0pcV5Dno5+4jh9sw==",
 			"license": "MIT",
-			"peer": true,
 			"bin": {
 				"acorn": "bin/acorn"
 			},
@@ -608,7 +607,6 @@
 			"resolved": "https://registry.npmjs.org/ajv/-/ajv-8.18.0.tgz",
 			"integrity": "sha512-PlXPeEWMXMZ7sPYOHqmDyCJzcfNrUr3fGNKtezX14ykXOEIvyK81d+qydx89KY5O71FKMPaQ2vBfBFI5NHR63A==",
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"fast-deep-equal": "^3.1.3",
 				"fast-uri": "^3.0.1",
@@ -752,7 +750,6 @@
 				}
 			],
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"baseline-browser-mapping": "^2.9.0",
 				"caniuse-lite": "^1.0.30001759",
@@ -1451,7 +1448,6 @@
 			"resolved": "https://registry.npmjs.org/jiti/-/jiti-2.6.1.tgz",
 			"integrity": "sha512-ekilCSN1jwRvIbgeg/57YFh8qQDNbwDb9xT/qu2DAHbFFZUicIl4ygVaAvzveMhMVr3LnpSKTNnwt8PoOfmKhQ==",
 			"license": "MIT",
-			"peer": true,
 			"bin": {
 				"jiti": "lib/jiti-cli.mjs"
 			}
@@ -1769,7 +1765,6 @@
 				}
 			],
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"nanoid": "^3.3.11",
 				"picocolors": "^1.1.1",
@@ -2394,7 +2389,6 @@
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 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"engines": {
 				"node": ">=12"
 			},
@@ -2416,9 +2410,9 @@
 			}
 		},
 		"node_modules/typescript": {
-			"version": "5.9.3",
-			"resolved": "https://registry.npmjs.org/typescript/-/typescript-5.9.3.tgz",
-			"integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
+			"version": "6.0.2",
+			"resolved": "https://registry.npmjs.org/typescript/-/typescript-6.0.2.tgz",
+			"integrity": "sha512-bGdAIrZ0wiGDo5l8c++HWtbaNCWTS4UTv7RaTH/ThVIgjkveJt83m74bBHMJkuCbslY8ixgLBVZJIOiQlQTjfQ==",
 			"devOptional": true,
 			"license": "Apache-2.0",
 			"bin": {
@@ -2499,7 +2493,6 @@
 			"resolved": "https://registry.npmjs.org/webpack/-/webpack-5.105.4.tgz",
 			"integrity": "sha512-jTywjboN9aHxFlToqb0K0Zs9SbBoW4zRUlGzI2tYNxVYcEi/IPpn+Xi4ye5jTLvX2YeLuic/IvxNot+Q1jMoOw==",
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@types/eslint-scope": "^3.7.7",
 				"@types/estree": "^1.0.8",
@@ -2730,7 +2723,7 @@
 			"version": "0.0.0",
 			"devDependencies": {
 				"postcss-preset-env": "file:../../../plugin-packs/postcss-preset-env",
-				"typescript": "^5.9.3"
+				"typescript": "^6.0.2"
 			}
 		},
 		"typescript/esm": {
@@ -2738,7 +2731,7 @@
 			"version": "0.0.0",
 			"devDependencies": {
 				"postcss-preset-env": "file:../../../plugin-packs/postcss-preset-env",
-				"typescript": "^5.9.3"
+				"typescript": "^6.0.2"
 			}
 		},
 		"typescript/esm--node-next": {
@@ -2746,7 +2739,7 @@
 			"version": "0.0.0",
 			"devDependencies": {
 				"postcss-preset-env": "file:../../../plugin-packs/postcss-preset-env",
-				"typescript": "^5.9.3"
+				"typescript": "^6.0.2"
 			}
 		},
 		"webpack/bundle-through": {
diff --git a/e2e/typescript/commonjs/package.json b/e2e/typescript/commonjs/package.json
index 2e17e5b2d5..098708ac5e 100644
--- a/e2e/typescript/commonjs/package.json
+++ b/e2e/typescript/commonjs/package.json
@@ -9,7 +9,7 @@
 	},
 	"devDependencies": {
 		"postcss-preset-env": "file:../../../plugin-packs/postcss-preset-env",
-		"typescript": "^5.9.3"
+		"typescript": "^6.0.2"
 	},
 	"volta": {
 		"extends": "../../package.json"
diff --git a/e2e/typescript/commonjs/tsconfig.json b/e2e/typescript/commonjs/tsconfig.json
index 042eefb8e2..347ce9058b 100644
--- a/e2e/typescript/commonjs/tsconfig.json
+++ b/e2e/typescript/commonjs/tsconfig.json
@@ -8,7 +8,10 @@
 		"module": "CommonJS",
 		"outDir": "./dist",
 		"target": "es2020",
-		"strict": true
+		"strict": true,
+		"types": [
+			"node"
+		]
 	},
 	"include": ["index.cts"],
 	"exclude": ["./index.cjs"],
diff --git a/e2e/typescript/esm--node-next/package.json b/e2e/typescript/esm--node-next/package.json
index b6e2e78d77..bdd56ca1e7 100644
--- a/e2e/typescript/esm--node-next/package.json
+++ b/e2e/typescript/esm--node-next/package.json
@@ -10,6 +10,6 @@
 	},
 	"devDependencies": {
 		"postcss-preset-env": "file:../../../plugin-packs/postcss-preset-env",
-		"typescript": "^5.9.3"
+		"typescript": "^6.0.2"
 	}
 }
diff --git a/e2e/typescript/esm--node-next/tsconfig.json b/e2e/typescript/esm--node-next/tsconfig.json
index 5233787eec..152f8cf0fd 100644
--- a/e2e/typescript/esm--node-next/tsconfig.json
+++ b/e2e/typescript/esm--node-next/tsconfig.json
@@ -9,7 +9,10 @@
 		"moduleResolution": "NodeNext",
 		"outDir": "./dist",
 		"target": "es2020",
-		"strict": true
+		"strict": true,
+		"types": [
+			"node"
+		]
 	},
 	"include": ["index.ts"],
 	"exclude": ["./index.mjs"],
diff --git a/e2e/typescript/esm/package.json b/e2e/typescript/esm/package.json
index 2949c04799..54a1d4565c 100644
--- a/e2e/typescript/esm/package.json
+++ b/e2e/typescript/esm/package.json
@@ -9,7 +9,7 @@
 	},
 	"devDependencies": {
 		"postcss-preset-env": "file:../../../plugin-packs/postcss-preset-env",
-		"typescript": "^5.9.3"
+		"typescript": "^6.0.2"
 	},
 	"volta": {
 		"extends": "../../package.json"
diff --git a/e2e/typescript/esm/tsconfig.json b/e2e/typescript/esm/tsconfig.json
index c0b8982d53..1e06b30638 100644
--- a/e2e/typescript/esm/tsconfig.json
+++ b/e2e/typescript/esm/tsconfig.json
@@ -9,7 +9,10 @@
 		"moduleResolution": "Node16",
 		"outDir": "./dist",
 		"target": "es2020",
-		"strict": true
+		"strict": true,
+		"types": [
+			"node"
+		]
 	},
 	"include": ["./index.mts"],
 	"exclude": ["./index.mjs"],
diff --git a/sites/package-lock.json b/sites/package-lock.json
index 71e337b53e..6b9677019a 100644
--- a/sites/package-lock.json
+++ b/sites/package-lock.json
@@ -141,16 +141,16 @@
 			}
 		},
 		"node_modules/@11ty/eleventy-plugin-rss": {
-			"version": "2.0.4",
-			"resolved": "https://registry.npmjs.org/@11ty/eleventy-plugin-rss/-/eleventy-plugin-rss-2.0.4.tgz",
-			"integrity": "sha512-LF60sGVlxGTryQe3hTifuzrwF8R7XbrNsM2xfcDcNMSliLN4kmB+7zvoLRySRx0AQDjqhPTAeeeT0ra6/9zHUQ==",
+			"version": "3.0.0",
+			"resolved": "https://registry.npmjs.org/@11ty/eleventy-plugin-rss/-/eleventy-plugin-rss-3.0.0.tgz",
+			"integrity": "sha512-kKW4DcR57xAyRx0e8gNhKh56ahHVEaAj8/TuXQDnw+B46ig2bWADJAlyj/GdV37IG5ja9dZ4SgKZrs/CHz6YWQ==",
 			"dev": true,
 			"license": "MIT",
 			"dependencies": {
-				"@11ty/eleventy-utils": "^2.0.0",
-				"@11ty/posthtml-urls": "^1.0.1",
-				"debug": "^4.4.0",
-				"posthtml": "^0.16.6"
+				"@11ty/eleventy-utils": "^2.0.7",
+				"@11ty/posthtml-urls": "^1.0.2",
+				"debug": "^4.4.3",
+				"posthtml": "^0.16.7"
 			},
 			"funding": {
 				"type": "opencollective",
@@ -262,7 +262,6 @@
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 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@babel/code-frame": "^7.29.0",
 				"@babel/generator": "^7.29.0",
@@ -2039,7 +2038,6 @@
 				}
 			],
 			"license": "MIT",
-			"peer": true,
 			"engines": {
 				"node": ">=20.19.0"
 			},
@@ -2063,7 +2061,6 @@
 				}
 			],
 			"license": "MIT",
-			"peer": true,
 			"engines": {
 				"node": ">=20.19.0"
 			}
@@ -4426,7 +4423,6 @@
 				}
 			],
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"baseline-browser-mapping": "^2.9.0",
 				"caniuse-lite": "^1.0.30001759",
@@ -7186,7 +7182,6 @@
 				}
 			],
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"nanoid": "^3.3.11",
 				"picocolors": "^1.1.1",
@@ -8020,7 +8015,6 @@
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 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"cssesc": "^3.0.0",
 				"util-deprecate": "^1.0.2"
@@ -8042,7 +8036,6 @@
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 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"posthtml-parser": "^0.11.0",
 				"posthtml-render": "^3.0.0"
@@ -8327,7 +8320,6 @@
 			"integrity": "sha512-yqjxruMGBQJ2gG4HtjZtAfXArHomazDHoFwFFmZZl0r7Pdo7qCIXKqKHZc8yeoMgzJJ+pO6pEEHa+V7uzWlrAQ==",
 			"dev": true,
 			"license": "MIT",
-			"peer": true,
 			"dependencies": {
 				"@types/estree": "1.0.8"
 			},
@@ -9524,7 +9516,7 @@
 			"license": "MIT-0",
 			"devDependencies": {
 				"@11ty/eleventy": "^3.1.0",
-				"@11ty/eleventy-plugin-rss": "^2.0.4",
+				"@11ty/eleventy-plugin-rss": "^3.0.0",
 				"@11ty/eleventy-plugin-syntaxhighlight": "^5.0.2",
 				"@babel/core": "^7.29.0",
 				"@babel/preset-env": "^7.29.0",
diff --git a/sites/postcss-preset-env/package.json b/sites/postcss-preset-env/package.json
index 45e9a8916f..9227ae1936 100644
--- a/sites/postcss-preset-env/package.json
+++ b/sites/postcss-preset-env/package.json
@@ -52,7 +52,7 @@
 	},
 	"devDependencies": {
 		"@11ty/eleventy": "^3.1.0",
-		"@11ty/eleventy-plugin-rss": "^2.0.4",
+		"@11ty/eleventy-plugin-rss": "^3.0.0",
 		"@11ty/eleventy-plugin-syntaxhighlight": "^5.0.2",
 		"@babel/core": "^7.29.0",
 		"@babel/preset-env": "^7.29.0",