I need to change the background shown in the knowledge interface to select the category, the choice of elements is confusing as shown in the image
You'll need to do a bit of digging, but this should get you started:
Modify the Theme - CA Service Management - 17.1 - CA Technologies Documentation
Let us know if you find the element.
If anyone else already knows, please chime in.
this KB is in Service Catalago Section about modify Branding, this caption is in Service Desk.
Inspect the element with chrome, it will tell you wich file and wich css class you need to change.