In Chrome in the Web Inspector styles editor if there is a background-image(url here), you can right click on that url and it will show a contextual menu allowing you copy that url or open in a new tab for instance. In Safari web inspector this does not work as expected. It shows a default contextual menu but not with the expected items. To note you can right click on a source such a css source file name in the sidebar in Safari and that contextual menu does appear with the correct items. Video of the issue: https://cl.ly/0O0u0i2z1z3D
This hasn't been ported to the new styles sidebar yet, but we should do this eventually.
<rdar://problem/36529200>
Thanks, glad this is in the queue to eventually be resolved in the new styles bar. Will be a small but big improvement for front-end devs.