diff --git a/src/Umbraco.Web.UI.Client/src/less/components/overlays.less b/src/Umbraco.Web.UI.Client/src/less/components/overlays.less
index bcdd1ba572..7a7ac15c6b 100644
--- a/src/Umbraco.Web.UI.Client/src/less/components/overlays.less
+++ b/src/Umbraco.Web.UI.Client/src/less/components/overlays.less
@@ -155,7 +155,7 @@
 @media (max-width: 500px) {
     .umb-overlay.umb-overlay-left {
         margin-left: 41px;
-        width: auto;
+        width: ~"(calc(~'100%' - ~'41px'))";
     }
 }