diff --git a/libreplan-webapp/src/main/webapp/planner/css/ganttzk.css b/libreplan-webapp/src/main/webapp/planner/css/ganttzk.css
index 5ab6ccd9b..9edfe7190 100644
--- a/libreplan-webapp/src/main/webapp/planner/css/ganttzk.css
+++ b/libreplan-webapp/src/main/webapp/planner/css/ganttzk.css
@@ -288,7 +288,7 @@ div.box.limiting-unassigned {
     border: 2px solid #F21CFF;
     height: 5px;
     width: 2px;
-    opacity: 0.5;
+    opacity: 0.75;
 }
 
 .first-timesheet-date {