update postcss-preset-env config

Author: skuadron45

postcss.config.js

@@ -1,6 +1,8 @@
 module.exports = {
   plugins: {
     'postcss-import': {},
-    'postcss-preset-env': {}
+    'postcss-preset-env': {
+      browsers: ['last 2 versions', '> 5%'],
+    }
   },
 };