diff --git a/src/room/InCallView.module.css b/src/room/InCallView.module.css
index 600a57de..0015cf20 100644
--- a/src/room/InCallView.module.css
+++ b/src/room/InCallView.module.css
@@ -150,6 +150,7 @@ Please see LICENSE in the repository root for full details.
   display: inline;
   z-index: 2;
   font-size: 32pt;
+  /* Reactions are "active" for 3 seconds (as per REACTION_ACTIVE_TIME_MS), give a bit more time for it to fade out. */
   animation-duration: 4s;
   animation-name: reaction-up;
   width: fit-content;