export class OStyleSheet extends Set < string > { private element : HTMLStyleElement ; constructor ( ) { super ( ) ; const el = document . createElement ( "style" ) ; el . setAttribute ( "data-ods" , "" ) ; this . element = document . head . appendChild ( el ) ; } inject ( key , styles ) { if ( this . has ( key ) ) return false ; this . element . innerHTML += styles ; this . add ( key ) ; return true ; } }