import Modifier from 'ember-modifier'; import { inject as service } from '@ember/service'; export default class CSSPropModifier extends Modifier { @service('-document') doc; didReceiveArguments() { const params = this.args.positional; const options = this.args.named; const returns = params[1] || options.returns; returns(this.doc.defaultView.getComputedStyle(this.element).getPropertyValue(params[0])); } }