add csp

app/javascript/elements/toggle_classes.js

@@ -0,0 +1,11 @@
+export default class extends HTMLElement {
+  connectedCallback () {
+    const button = this.querySelector('a, button')
+
+    button.addEventListener('click', () => {
+      this.dataset.classes.split(' ').forEach((cls) => {
+        button.classList.toggle(cls)
+      })
+    })
+  }
+}