diff --git a/src/components/Popups/PopupBase.scss b/src/components/Popups/PopupBase.scss
index 47e9b4ed5..19410a526 100644
--- a/src/components/Popups/PopupBase.scss
+++ b/src/components/Popups/PopupBase.scss
@@ -9,7 +9,7 @@
     .ba-Popup {
         @include common-typography;
 
-        z-index: 1;
+        z-index: 1; // Make sure popup is showing above Preview controls and left/right arrows
 
         // Changing z-index causes page to flicker in IE11
         // The following media query is specific to IE10+