diff --git a/ui/layout.css b/ui/layout.css
index b91b343d..26ba8adc 100644
--- a/ui/layout.css
+++ b/ui/layout.css
@@ -454,6 +454,11 @@ button:hover {
   right: 5px;
   border-radius: 50%;
   background: blue;
+  box-shadow: 0px 0px 7px 0px black;
+  /*border: solid 1px white;*/
+
+  /*border: solid 1px black;*/
+
 }
 .marks-visible.viewer .marked.image[orientation="270"][flipped*="vertical"][flipped*="horizontal"]:after,
 .marks-visible.viewer .marked.image:not([orientation])[flipped*="vertical"]:after,
diff --git a/ui/layout.less b/ui/layout.less
index 56c07573..b773fd0f 100755
--- a/ui/layout.less
+++ b/ui/layout.less
@@ -522,6 +522,12 @@ button:hover {
 
 	border-radius: 50%;
 	background: blue;
+
+	/* make the mark stand out if it is over an image with similar 
+	color/density */
+	box-shadow: 0px 0px 7px 0px black;
+	/*border: solid 1px white;*/
+	/*border: solid 1px black;*/
 }
 .marks-visible.viewer .marked.image[orientation="270"][flipped*="vertical"][flipped*="horizontal"]:after,
 .marks-visible.viewer .marked.image:not([orientation])[flipped*="vertical"]:after,