constructor () {
    /**
     * Helpers class
     * @type {Helpers}
     */
    this.Helpers = new Helpers();

    /**
     * Store for currently active element
     * @type {Element}
     */
    this.activeElement = undefined;

    /**
     * Store for last active elemet
     * @type {Element}
     */
    this.lastActive = undefined;

    /**
     * Store for stacked elements
     * @type {Array}
     */
    this.stackedElements = [];

    /**
     * All elements that can get focus, can be tabbed in a modal
     * @type {Array}
     */
    this.tabbableElements = [
      'a[href]',
      'area[href]',
      'input:not([disabled])',
      'select:not([disabled])',
      'textarea:not([disabled])',
      'button:not([disabled])',
      'iframe',
      'object',
      'embed',
      '[tabindex]:not([tabindex="-1"])',
      '[contenteditable]'
    ];

    // We use jQuery if the browser doesn't support CustomEvents
    if (!window.CustomEvent && !window.$) {
      throw new Error('This browser doesn\'t support CustomEvent - please include jQuery.');
    }

    /**
     * All events
     */
    this.events();

    /**
     * Inject iframes
     */
    this.injectIframes();
  }
CSS Modal
http://drublic.github.com/css-modal

@author Hans Christian Reinl - @drublic