Example of How to use Custom Field "Display in List" to highlight values by color

Hello, there was an old post way back on the old forms where a user used the customization options on the “Advanced” tab of Customize > Field Customization to highlight the values in a certain color based on that value. I believe the example was a basic Low,Medium,High, with “High” showing in Red in the list. 

We are able to get HTML style values inserted into the “Display in Form” options, but cant seem to get anything to work in the Display In List box.

Anyone doing this successfully or have any examples?

Thank you for any guidance!