Conditional colors for line chart legend

Hello, 

I am trying to create a line chart to display my  data in Power BI. I want the following conditions to be met:

1. When I select the "All" option in my dashboard slicer, all lines on my line chart should be displayed in gray.
2. When I select a single value in my dashboard slicer, the line displayed on my line chart should be in orange.

When I have all sites: 

When I have only one selected site in the slicer: 

I have tried several methods but have not been able to find a solution that meets these requirements. I would like to know how to set up my line chart to correctly display colors when these conditions are met.

If anyone could provide any guidance or suggestions on how to achieve this goal, I would greatly appreciate it. Thank you!