--- a/calendar/base/themes/common/calendar-attendees.css
+++ b/calendar/base/themes/common/calendar-attendees.css
@@ -6,16 +6,20 @@
 @namespace html url("http://www.w3.org/1999/xhtml");
 
 /* this is for attendee and organizer decoration in summary and event dialog */
 html|input.textbox-addressingWidget {
     width: 100%;
     background-color: transparent !important;
     flex: 1;
 }
+html|input.textbox-addressingWidget:disabled {
+    color: inherit;
+    opacity: 0.5;
+}
 
 #item-attendees-box {
     -moz-appearance: listbox;
     margin: 2px 4px 0;
     overflow-y: auto;
     min-height: 54px; /*at least two rows - otherwise a scrollbar (if required) wouldn't appear*/
 }
 

--- a/calendar/base/themes/common/dialogs/calendar-event-dialog.css
+++ b/calendar/base/themes/common/dialogs/calendar-event-dialog.css
@@ -1,17 +1,17 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 @namespace html url("http://www.w3.org/1999/xhtml");
 
 dialog {
   --eventBorderColor: #8d8e90;
-  --eventWidgetBorderColor: #cacaff;
+  --eventWidgetBorderColor: #aaaabc;
   --eventGridStartBorderColor: #bdbec0;
 }
 
 dialog[systemcolors] {
   --eventBorderColor: ThreeDShadow;
   --eventWidgetBorderColor: ThreeDShadow;
   --eventGridStartBorderColor: ThreeDShadow;
 }
@@ -447,17 +447,18 @@ label.label {
   min-width: 150px;
   min-height: 150px;
 }
 
 .listbox-noborder {
   -moz-appearance: none;
   margin: 0px 0px;
   border: 1px solid var(--eventBorderColor);
-  background-color: #fff;
+  background-color: -moz-Field;
+  color: -moz-FieldText;
 }
 
 #timebar {
   overflow: hidden;
 }
 
 #timebar > .listbox-noborder {
   border-bottom-style: none;