Add extra-small breakpoint

tailwind.config.js

@@ -25,7 +25,11 @@ module.exports = {
       '1-1/3': '1 1 33.3333333%',
       '1-1/2': '1 1 50%',
     },
-    extend: {},
+    extend: {
+      screens: {
+        'xs': '400px',
+      }
+    },
   },
   variants: {
     extend: {