With the new menu system, it's more difficult to switch from company settings to system settings and vice-versa. Add the following markup inside left_container:

<div class="btn-group btn-group-justified" role="group" aria-label="..." style="
display: table;
width: 100%;
table-layout: fixed;
border-collapse: separate;
margin-top: 5px;
margin-bottom: 5px;
position: relative;
vertical-align: middle;
">
<div class="btn-group" role="group" style="
display: table-cell;
float: none;
width: 1%;
position: relative;
vertical-align: middle;
">
<button type="button" class="btn btn-default" style="width: 100%;border-radius: 4px 0 0 4px;">Company</button>
</div>
<div class="btn-group" role="group" style="
display: table-cell;
float: none;
width: 1%;
position: relative;
vertical-align: middle;
">
<button type="button" class="btn btn-default" style="width: 100%;border-radius: 0 4px 4px 0;">System</button>
</div>
</div>

*NOTE!* The markup above contains inline styles, which should be stripped from the markup. We need to include the button group styles from Bootstrap referenced in the above class names.