--- a/toolkit/components/alerts/resources/content/alert.css
+++ b/toolkit/components/alerts/resources/content/alert.css
@@ -1,14 +1,14 @@
 /* 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/. */
 
 #alertBox[animate] {
-  animation-duration: 12s;
+  animation-duration: 20s;
   animation-fill-mode: both;
   animation-name: alert-animation;
 }
 
 #alertBox[animate]:not([clicked]):not([closing]):hover {
   animation-play-state: paused;
 }
 

--- a/toolkit/components/alerts/resources/content/alert.js
+++ b/toolkit/components/alerts/resources/content/alert.js
@@ -141,17 +141,17 @@ function prefillAlertInfo() {
         document.getElementById("alertImage").setAttribute("src", window.arguments[0]);
       }
     case 0:
       break;
   }
 }
 
 function onAlertLoad() {
-  const ALERT_DURATION_IMMEDIATE = 12000;
+  const ALERT_DURATION_IMMEDIATE = 20000;
   let alertTextBox = document.getElementById("alertTextBox");
   let alertImageBox = document.getElementById("alertImageBox");
   alertImageBox.style.minHeight = alertTextBox.scrollHeight + "px";
 
   sizeToContent();
 
   if (gReplacedWindow && !gReplacedWindow.closed) {
     moveWindowToReplace(gReplacedWindow);