Test CSS.forcePseudoStates method for :focus setting :focus-within state across shadow root boundaries
Shadow mode: open
#inner background color without forced focus: default
#host border without forced focus: 0px none rgb(0, 0, 0)
#inner background color with forced focus:  background: red; 
#host border with forced focus: 1px solid rgb(0, 0, 0)
Shadow mode: closed
#inner background color without forced focus: default
#host border without forced focus: 0px none rgb(0, 0, 0)
#inner background color with forced focus:  background: red; 
#host border with forced focus: 1px solid rgb(0, 0, 0)