#where  = none | where  =  |  |  |  |  |  | where  = image( ? [ ? , ? ]! ) = image-set( # ) = element(  ) = paint( , ? ) = cross-fade(  , ? ) =  |  |  |  | where  = ltr | rtl =  |  =  |  |  |  |  |  | currentcolor |  = [  |  ] [  || type() ] =  = ? &&  =  |  = linear-gradient( [  | to  ]? ,  ) = repeating-linear-gradient( [  | to  ]? ,  ) = radial-gradient( [  ||  ]? [ at  ]? ,  ) = repeating-radial-gradient( [  ||  ]? [ at  ]? ,  ) = conic-gradient( [ from  ]? [ at  ]?,  )where  = rgb( {3} [ /  ]? ) | rgb( {3} [ /  ]? ) | rgb( #{3} , ? ) | rgb( #{3} , ? ) = rgba( {3} [ /  ]? ) | rgba( {3} [ /  ]? ) | rgba( #{3} , ? ) | rgba( #{3} , ? ) = hsl(    [ /  ]? ) | hsl( , , , ? ) = hsla(    [ /  ]? ) | hsla( , , , ? ) = [ left | right ] || [ top | bottom ] = [  [, ]? ]# ,  = circle | ellipse = closest-side | farthest-side | closest-corner | farthest-corner |  | {2} = [ [ left | center | right ] || [ top | center | bottom ] | [ left | center | right |  ] [ top | center | bottom |  ]? | [ [ left | right ]  ] && [ [ top | bottom ]  ] ] = [  [, ]? ]# , where  =  |  =  |  =  ? =  =  |  =  && ? = where  = {1,2} = {1,2} =  |