CSS for ember view tag

I would like to set the z-index for an ember view within the view class but ember keeps throwing the error:

DEPRECATION: Dynamic content in the `style` attribute is not escaped and may pose a security risk.

An abbreviated version of my class is this:

App.ModalComponent = Ember.Component.extend({
    layoutName: 'components/modal',
    classNames: ['modal', 'fade'],
    attributeBindings: ['style'],
    style: function() {
        return 'z-index:131071';
    }.property()
});

Do any more seasoned ember gurus know a more appropriate way to set custom style on an Ember View? Thanks!