[解決済み] フレックスコンテナ内の残りの高さまたは幅を埋める

.ar-course-nav {
  cursor: pointer;
  padding: 8px 12px 8px 12px;
  border-radius: 8px;
}
.ar-course-nav:hover {
  background-color: rgba(0, 0, 0, 0.1);
}

<br/>
<br/>
<div class="ar-course-nav" style="display:flex; justify-content:space-between;">
  <div style="width:96%;">
    <div style="overflow:hidden; white-space:nowrap; text-overflow:ellipsis;">
      <strong title="Course Name Which is Really Quite Long And Does Go On a Bit But Then When You Think it's Stopped it Keeps on Going for even longer!">
                Course Name Which is Really Quite Long And Does Go On a Bit But Then When You Think it's Stopped it Keeps on Going for even longer!
            </strong>
    </div>
    <div style="width:100%; display:flex; justify-content:space-between;">
      <div style="color:#555555; margin-right:8px; overflow:hidden; white-space:nowrap; text-overflow:ellipsis;" title="A really really really really really really really really really really really long department name">
        A really really really really really really really really really really really long department name
      </div>
      <div style="color:#555555; text-align:right; white-space:nowrap;">
        Created: 21 September 2016
      </div>
    </div>
  </div>
  <div style="margin-left:8px;">
    <strong>&gt;</strong>
  </div>
</div>