type MarginProperty = "margin-block-start" | "margin-block-end" | "margin-inline-start" | "margin-inline-end" ; type MarginUnit = "px" | "vh" | "vw" ; type MarginValue = `${ number }${ MarginUnit }` ; type MarginDeclaration = [ MarginProperty , MarginValue ] ; const margin = [ "margin-block-start" , "20vh" ] ;