How to use custom styling with ui-select in AngularJS?

Question

I use Angular UI https://github.com/angular-ui/ui-select.

I have a slight issue with my usage of the style. I would like to avoid altogether having their pre-made design included and want to apply my own custom made styling.

Basically I was using this custom Select2 style with jQuery before and I want to upgrade it to AngularJS.

The issue is that when I'm applying my css class to the HTML element it's not applying any of the styling I have.

This is my current code:

<ui-select search-enabled="true" class="custom-select" ng-model="selected.value">
    <ui-select-match placeholder="Select a value">
        <span ng-bind="$select.selected.name"></span>
    </ui-select-match>
    <ui-select-choices repeat="item in (defaultValues | filter: $select.search) track by item.id">
        <span ng-bind="item.name"></span>
    </ui-select-choices>
</ui-select>

My CSS style is custom-select which is setting everything correctly with jQuery + Select2.

Is it possible to use my current jQuery Select2 field's CSS with AngularJS the exact same way as before without changing anything major?

Any alternate options here?