How to change the background color of the icon that shows the chat queue waiting number

Unable to see the chat queue waiting number, the icon is all white.  

After inspecting the page, we confirmed the number (text) is there, but the background and text are white, #ffffff. 

The color that can be change is the background color, below the way to do it: 

1 Navigate to System Properties --> Basic Configuration UI16
2. Search by "Navigation selected tab divider bar color" ( css.$nav-highlight-bar-active )

The current color should be white (#ffffff), so change it to a different color.