Referenced image files are not visible in runtime

[nevarman]

Hi,
The referenced image files in the stylesheet below are not visible in runtime. I assume they are editor only assets.
https://github.com/Sahasrara/ContextualMenuPlayer/blob/ffc803666acc3a7ad58665bd0d825eb2bcdb79bb/Resources/ContextualMenu/ContextualMenu.uss#L102