Added transitions for header bar content colours.

resources/report/css/overrides.css

@@ -14,6 +14,7 @@ html /deep/ paper-item[disabled] > core-icon {
 /* Change color of disabled icon buttons to match Material Design spec. */
 paper-icon-button[disabled] {
     color: rgba(255, 255, 255, 0.30);
+    transition: color 0.6s;
 }
 /* This override change the positioning of the progress dialog to adapt to content changes. */
 #progressDialog {

resources/report/html/loot-dropdown-menu.html

@@ -37,6 +37,9 @@ it a <select>-like API. This means:
         :host(.dark) paper-dropdown-menu {
             border-bottom-color: rgba(255, 255, 255, 0.12);
         }
+        paper-dropdown-menu[disabled]::shadow #label {
+            transition: color 0.6s;
+        }
         :host(.dark) paper-dropdown-menu::shadow #label {
             color: white;
         }