anchor.diff:              let [<Literal>] IsRadiusless = "is-radiusless"
               let [<Literal>] IsShadowless = "is-shadowless"
               let [<Literal>] IsUnselectable = "is-unselectable"
  +            let [<Literal>] IsSrOnly = "is-sr-only"
   
       let internal ofBackground level =
           match level with
  
positive.code:         | IsHidden of Screen * bool
          | IsInvisibleOnly of Screen * bool
          | IsHiddenOnly of Screen * bool
  
      type internal Options =
          { BackgroundColor : string option
  
negative.code:           IsInvisibleOnly : string
            IsHiddenOnly : string
            Display : string
            DisplayOnly : string
            IsSrOnly : string }
  
          static member Empty =
              { BackgroundColor = None
  