netlify identity widget script in head

_layouts/default.html

@@ -13,6 +13,7 @@
     {% include head.html %}
     {% include head/custom.html %}
 
+    <script src="https://identity.netlify.com/v1/netlify-identity-widget.js"></script>
     <script>
     if (window.netlifyIdentity) {
         window.netlifyIdentity.on("init", user => {