index.js
function getCss () {
  return checkTime().then(function(isOld){

    if (isOld){ 
      return writeCss().then(function(str){
        if (!str) return readCss()
        return str
      })
    }
    return readCss()
  })
}
function getCss () {
  return checkTime().then(function(isOld){

    if (isOld){ 
      return writeCss().then(function(str){
        if (!str) return readCss()
        return str
      })
    }
    return readCss()
  })
}
function getCss ( ) { return checkTime ( ) . then ( function ( isOld ) { if ( isOld ) { return writeCss ( ) . then ( function ( str ) { if ( ! str ) return readCss ( ) return str } ) } return readCss ( ) } ) }
It gets the css local or remote.
@private
@return {Promise} - it passes {String} with github's css to the next `then`.
It gets the css local or remote .