Optional peer

Author: Mark Skelton

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@widen/postcss-css-in-js",
-  "version": "0.37.3",
+  "version": "0.37.4",
   "description": "PostCSS syntax for parsing CSS in JS literals",
   "keywords": [
     "postcss",
@@ -78,5 +78,13 @@
     "postcss-safe-parser": "^4.0.2",
     "prettier": "^2.4.1",
     "remark-cli": "^9.0.0"
+  },
+  "peerDependencies": {
+    "postcss": ">=7.0.0"
+  },
+  "peerDependenciesMeta": {
+    "postcss": {
+      "optional": true
+    }
   }
 }