emphasis
Specifies a glow effect range of the emphasis circle, in pixels. If 0,0 values are provided, it renders the circle as a solid color. The first value specifies the start of the glow effect where it is equal to the circle's color, the second is the end, where it's fully transparent. Between the two values the effect is linearly faded out. Default value: 0,0.
This is an Expression representation of "emphasis-circle-glow-range".