diff --git a/README.md b/README.md
index 1b047f8..d722104 100644
--- a/README.md
+++ b/README.md
@@ -343,7 +343,8 @@ Three single-file HTML frontends, each served by its own backend at `/ui/`:
 
 Features: search box, Enter-key support, suggestion chips (trees, water, people,
 buildings, sky, street, night, cars), result grid with thumbnails and similarity
-scores in percent.
+scores in percent. Click any photo to view it full size in a lightbox overlay;
+close with a click anywhere or `Escape`.
 
 ---