diff --git a/web/viewer.css b/web/viewer.css
index 3dfae373e..deb9173d6 100644
--- a/web/viewer.css
+++ b/web/viewer.css
@@ -1127,7 +1127,6 @@ html[dir='rtl'] .verticalToolbarSeparator {
 }
 
 .thumbnailImage {
-  transition-duration: 150ms;
   border: 1px solid transparent;
   box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.5), 0 2px 8px rgba(0, 0, 0, 0.3);
   opacity: 0.8;
@@ -1139,7 +1138,6 @@ html[dir='rtl'] .verticalToolbarSeparator {
 .thumbnailSelectionRing {
   border-radius: 2px;
   padding: 7px;
-  transition-duration: 150ms;
 }
 
 a:focus > .thumbnail > .thumbnailSelectionRing > .thumbnailImage,