Viewing that with Swarth set to its normal "stylesheet processor" results in... basically no change other than the banner at the top becoming a lighter color.
In the meantime, try using the Simple Stylesheet color method instead. AFAICT, that site uses CSS variables for its colors and would require writing a special case for those values.
https://linustechtips.com/topic/1099830-usb-type-c-gen-1-can-it-output-video/
Viewing that with Swarth set to its normal "stylesheet processor" results in... basically no change other than the banner at the top becoming a lighter color.