Add autoprefixer and cssnano support

.stylelintrc

@@ -1,6 +1,14 @@
 extends: stylelint-config-standard
 
+plugins:
+  - stylelint-no-unsupported-browser-features
+
 rules:
+  plugin/no-unsupported-browser-features:
+    - true
+    - severity: warning
+      ignore: ['rem']
+
   color-hex-case: lower
   declaration-colon-newline-after: null
   selector-list-comma-newline-after: null