early dark mode support using #dark

wwwroot/css/site.css

@@ -35,6 +35,11 @@ textarea {
     border-width: 0;
 }
 
+    textarea.dark {
+        background-color: #222;
+        color: #ddd;
+    }
+
 #saved-indicator {
     position: fixed;
     bottom: -40px;

wwwroot/js/site.js

@@ -22,6 +22,11 @@
 
 $(function () {
 
+    // set dark mode
+    if (window.location.hash == '#dark') {
+        $('textarea').addClass('dark');
+    }
+
     var timer = null;
     let ignoredKeyCodes = [17, 18, 20, 27, 37, 38, 39, 40, 91];