diff --git a/css/leptonChrome.css b/css/leptonChrome.css
index b0799b1..58fd82b 100644
--- a/css/leptonChrome.css
+++ b/css/leptonChrome.css
@@ -3833,17 +3833,15 @@
         width: 18em;
         max-width: 36em;
         /* Animation */
-        transition: margin-inline-start 0.25s var(--animation-easing-function), opacity 0.25s ease-in-out,
-          visibility 0s linear !important;
-        will-change: margin-inline-start, opacity, visibility;
+        transition: margin-inline-start 0.25s var(--animation-easing-function), visibility 0s linear !important;
+        will-change: margin-inline-start, visibility;
       }
       #sidebar-box[hidden="true"] {
         display: flex !important;
         display: -moz-box !important;
         margin-inline-start: -18em;
-        opacity: 0;
         visibility: collapse;
-        transition-delay: 0s, 0s, 0.25s !important;
+        transition-delay: 0s, 0.25s !important;
       }
     }
     /*- Titlebar & Full Screen -------------------------------------------------*/
@@ -18040,17 +18038,15 @@
     width: 18em;
     max-width: 36em;
     /* Animation */
-    transition: margin-inline-start 0.25s var(--animation-easing-function), opacity 0.25s ease-in-out,
-      visibility 0s linear !important;
-    will-change: margin-inline-start, opacity, visibility;
+    transition: margin-inline-start 0.25s var(--animation-easing-function), visibility 0s linear !important;
+    will-change: margin-inline-start, visibility;
   }
   #sidebar-box[hidden="true"] {
     display: flex !important;
     display: -moz-box !important;
     margin-inline-start: -18em;
-    opacity: 0;
     visibility: collapse;
-    transition-delay: 0s, 0s, 0.25s !important;
+    transition-delay: 0s, 0.25s !important;
   }
 }
 @media (prefers-reduced-motion: no-preference) and (-moz-bool-pref: "userChrome.decoration.animate") {
diff --git a/css/leptonChromeESR.css b/css/leptonChromeESR.css
index a5e6c9c..be4822b 100644
--- a/css/leptonChromeESR.css
+++ b/css/leptonChromeESR.css
@@ -4153,17 +4153,15 @@
         width: 18em;
         max-width: 36em;
         /* Animation */
-        transition: margin-inline-start 0.25s var(--animation-easing-function), opacity 0.25s ease-in-out,
-          visibility 0s linear !important;
-        will-change: margin-inline-start, opacity, visibility;
+        transition: margin-inline-start 0.25s var(--animation-easing-function), visibility 0s linear !important;
+        will-change: margin-inline-start, visibility;
       }
       #sidebar-box[hidden="true"] {
         display: flex !important;
         display: -moz-box !important;
         margin-inline-start: -18em;
-        opacity: 0;
         visibility: collapse;
-        transition-delay: 0s, 0s, 0.25s !important;
+        transition-delay: 0s, 0.25s !important;
       }
     }
     /*- Titlebar & Full Screen -------------------------------------------------*/
diff --git a/src/decoration/_animate.scss b/src/decoration/_animate.scss
index bedb5c5..3077987 100644
--- a/src/decoration/_animate.scss
+++ b/src/decoration/_animate.scss
@@ -119,16 +119,14 @@ xul|search-textbox.tabsFilter,
     max-width: 36em;
 
     /* Animation */
-    transition: margin-inline-start 0.25s var(--animation-easing-function), opacity 0.25s ease-in-out,
-      visibility 0s linear !important;
-    will-change: margin-inline-start, opacity, visibility;
+    transition: margin-inline-start 0.25s var(--animation-easing-function), visibility 0s linear !important;
+    will-change: margin-inline-start, visibility;
 
     &[hidden="true"] {
       @include Box(true);
       margin-inline-start: -18em;
-      opacity: 0;
       visibility: collapse;
-      transition-delay: 0s, 0s, 0.25s !important;
+      transition-delay: 0s, 0.25s !important;
     }
   }
 }