Fix incorrect notification border color in dark.css

install/deb/themes/dark.css

@@ -949,7 +949,7 @@ a {
   color: #dadada;
   border-bottom-left-radius: 6px;
   border-bottom-right-radius: 6px;
-  border: 1px solid #282828;
+  border: 1px solid #404040;
   border-top: none;
 }