diff --git a/themes/default/theme.css b/themes/default/theme.css
index f0103e3a8..af964011f 100644
--- a/themes/default/theme.css
+++ b/themes/default/theme.css
@@ -342,6 +342,7 @@ TD.calDayCellFull, TD.calDayCellEmpty {
 }
 .thumbnails IMG {
 	vertical-align: middle;
+  max-width: 100%;
 }
 
 .thumbnails SPAN.thumbLegend {