sky
Defines a radial color gradient with which to color the sky. The color values can be interpolated with an expression using sky-radial-progress. The range 0, 1 for the interpolant covers a radial distance (in degrees) of 0, `sky-gradient-radius` centered at the position specified by sky-gradient-center. Default value: ["interpolate","linear","sky-radial-progress",0.8,"#87ceeb",1,"white"].