docs: function Overlay(options) {
  	if (!(this instanceof Overlay)) return new Overlay(options);
  
  	Emitter.call(this);
  
  	extend(this, options);
  
  	if (!this.container) {
  		this.container = document.body || document.documentElement;
  	}
  
  	//create overlay element
  	this.element = document.createElement('div');
  	this.element.classList.add('popoff-overlay');
  
  	if (this.closable) {
  		this.element.addEventListener('click', e => {
  			this.hide();
  		});
  		this.element.classList.add('popoff-closable');
  	}
  }