Multi-line menu items are badly displayed at `nav--super-vertical`

[jackens]

Multi-line menu items are badly displayed at nav--super-vertical

To see what i am meaning simply change lines

<label for="nav-collapsible-1">Components</label>
<div class="nav-collapsible-links">
  <a href="docs/alerts.html">Alerts</a>

of docs/index.html to something like

<label for="nav-collapsible-1">Components: Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua</label>
<div class="nav-collapsible-links">
  <a href="docs/alerts.html">Alerts: Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua</a>