Change background color of scroll slider addon

[_Luccer]

https://lucastarace.ch/off-camera/
Mac OS, Chrome/Safari
I’d like to change the background color of the Scroll Slider Addon so that it matches my website’s design.
I’ve already tried changing the Row Background Color as well as the main background color in the Gridder, but neither seems to affect the background of the Scroll Slider Addon.

Is there a separate setting for the Scroll Slider’s background color, or does this need to be changed via custom CSS?

Thanks for your help!