⇒ Back Side will be represented by two diagonal lines, across the CardElement Card. page 
initializeBack back := BlElement new constraintsDo: [ :c | c horizontal matchParent. c vertical matchParent ]. back addChild: (BlLineElement new border: (BlBorder paint: self foregroundColor width: 1); fromAnchor: (BlElementTopLeftAnchor new referenceElement: back); toAnchor: (BlElementBottomRightAnchor new referenceElement: back); yourself); addChild: (BlLineElement new border: (BlBorder paint: self foregroundColor width: 1); fromAnchor: (BlElementTopRightAnchor new referenceElement: back); toAnchor: (BlElementBottomLeftAnchor new referenceElement: back); yourself).