TimelineQueueButtonHeader: make it sticky

app/soapbox/components/status_list.js

@@ -82,6 +82,7 @@ export default class StatusList extends ImmutablePureComponent {
   }
 
   handleDequeueTimeline = () => {
+    window.scrollTo({ top: 0, behavior: 'smooth' });
     const { onDequeueTimeline, timelineId } = this.props;
     if (!onDequeueTimeline || !timelineId) return;
     onDequeueTimeline(timelineId);

app/soapbox/components/timeline_queue_button_header.js

@@ -2,6 +2,7 @@ import React from 'react';
 import PropTypes from 'prop-types';
 import { injectIntl } from 'react-intl';
 import classNames from 'classnames';
+import SvgIcon from 'soapbox/components/svg_icon';
 
 export default @injectIntl
 class TimelineQueueButtonHeader extends React.PureComponent {
@@ -27,6 +28,7 @@ class TimelineQueueButtonHeader extends React.PureComponent {
     return (
       <div className={classes}>
         <a className='timeline-queue-header__btn' onClick={onClick}>
+          <SvgIcon src={require('@tabler/icons/icons/arrow-bar-to-up.svg')} />
           {(count > 0) && intl.formatMessage(message, { count })}
         </a>
       </div>

app/styles/components/timeline-queue-header.scss

@@ -1,29 +1,44 @@
 .timeline-queue-header {
-  display: block;
+  display: flex;
-  width: 100%;
+  align-items: center;
-  max-height: 46px;
+  justify-content: space-evenly;
-  position: relative;
+  max-height: 30px;
+  position: sticky;
+  top: 60px;
+  margin: 8px auto;
+  background-color: var(--brand-color);
+  color: #fff;
   border-bottom: 1px solid;
   border-top: 1px solid;
   border-color: var(--brand-color--faint);
+  border-radius: 100px;
   transition: max-height 150ms ease;
   overflow: hidden;
   opacity: 1;
+  left: 0;
+  right: 0;
+  padding: 0 10px;
+  z-index: 999;
+
+  .svg-icon {
+    margin-right: 5px;
+  }
 
   &.hidden {
     max-height: 0;
     opacity: 0;
+    margin: 0;
   }
 
   &__btn {
-    display: block;
+    display: flex;
-    width: 100%;
-    height: 100%;
-    text-align: center;
     line-height: 46px;
     font-size: 14px;
     cursor: pointer;
-    color: var(--primary-text-color);
+    color: #fff;
+    white-space: nowrap;
+    align-items: center;
+    justify-content: center;
 
     span {
       height: 46px;