Implement darkmode using stimulus.

assets/controllers/common/darkmode_controller.js

@@ -0,0 +1,41 @@
+import {Controller} from "@hotwired/stimulus";
+import Darkmode from "darkmode-js/src";
+import "darkmode-js"
+
+export default class extends Controller {
+
+    _darkmode;
+
+    connect() {
+        if (typeof window.getComputedStyle(document.body).mixBlendMode == 'undefined') {
+            console.warn("The browser does not support mix blend mode. Darkmode will not work.");
+            return;
+        }
+
+        try {
+            const darkmode = new Darkmode();
+            this._darkmode = darkmode;
+
+            //Unhide darkmode button
+            this._showWidget();
+
+            //Set the switch according to our current darkmode state
+            const toggler = document.getElementById("toggleDarkmode");
+            toggler.checked = darkmode.isActivated();
+        }
+        catch (e)
+        {
+            console.error(e);
+        }
+
+
+    }
+
+    _showWidget() {
+        this.element.classList.remove('hidden');
+    }
+
+    toggleDarkmode() {
+        this._darkmode.toggle();
+    }
+}