Accessibility classes

Visually hides content but remains accessible to screen reader users
Visually hides content until focussed. For elements other than anchors & form elements, use in conjunction with tabindex, to allow them to recieve keyboard focus

Example Code:

<!-- "Skip Navigation" Link, only visible to screen readers -->
<a class="sr-only" href="#maincontent">Skip to main content</a>

<!-- Visually hides content until focussed -->
<div class="show-me-when-focused" tabindex="0">
  <p>This content is visible on focus</p>