selectively apply a css class to our "focused" pulse list item.

frontend/src/css/pulse.css

@@ -55,6 +55,10 @@
   opacity: 1;
 }
 
+.PulseListItem.PulseListItem--focused {
+
+}
+
 .DangerZone:hover {
   border-color: var(--error-color);
   transition: border .3s ease-in;

frontend/src/pulse/components/PulseListItem.jsx

 import React, { Component, PropTypes } from "react";
 
+import cx from "classnames";
+
 import PulseListChannel from "./PulseListChannel.jsx";
 
 export default class PulseListItem extends Component {
@@ -20,7 +22,7 @@ export default class PulseListItem extends Component {
         let { pulse, formInput, user } = this.props;
 
         return (
-            <div ref="pulseListItem" className="PulseListItem bordered rounded mb2 pt3">
+            <div ref="pulseListItem" className={cx("PulseListItem bordered rounded mb2 pt3", {"PulseListItem--focused": this.props.scrollTo})}>
                 <div className="flex px4 mb2">
                     <div>
                         <h2 className="mb1">{pulse.name}</h2>