ReactCSSTransitionGroup -- where my styles at?

I’m migrating a basic blog app with React commenting system over to react_on_rails from react-rails. I had trouble getting react-bootstrap to work with the standard gem, and I found out that is not going to be around forever, so I thought I should learn the webpack ecosystem anyway.

I have a CSSTransitionGroup that highlights comments as they enter the list:

20   ┆ ┆ ┆ <ReactCSSTransitionGroup transitionName="comment" transitionEnterTimeout={1000} transitionLeaveTimeout={300} >
21   ┆ ┆ ┆ ┆ {renderComments}
22   ┆ ┆ ┆ </ReactCSSTransitionGroup>

I had to change around the means of invoking the CSSTransitionGroup; in react-rails, all you have to do is turn on the addons in config/application.rb. To be absolutely sure I wasn’t improperly importing the javascript, I cribbed the import line from shakacode’s tutorial:

import ReactCSSTransitionGroup from react/lib/ReactCSSTransitionGroup’

There are no complaints from rails or webpack/the browser about the javascript, but the highlighting isn’t appearing when new comments enter the list. That highlighting is currently at app/assets/stylesheets/comments.scss:

.comment-enter {
background-color: #ffeebb;

.comment-enter.comment-enter-active {
background-color: white;
transition: background-color 1000ms ease-in;

I’m pretty sure this is a case of the style not being pulled in by webpack. So where should I have stylesheets so that they’re getting into the pipeline?

EDIT: Actually, I’m totally sure this is what’s happening. My other styles from app/assets/stylesheets/comments.css.scss aren’t being applied, either.