Using a custom DOM element for the container property

[zion]

I have a .grid-container element that I want this message to display in, however, when I add document.getElementByClassName('.grid-container') to the container property in my env file I get:

Could not require 'ember-cli-build.js': document is not defined

Seems that upon building the build files aren't sure what document is. Is there a way I could update the config object after the app has been built? That sounds like a bad idea, however, not sure what else to do.

Or maybe the addon could accept a string of a class name or id of an element and the addon could translate that to a DOM object for BU?

I could do a PR for this, with a little direction on the desired solution here.