1.1.1 - Screen reader Only
Source: atoms/a11y/_screen-reader.scss, line 27
.screen-reader-only allow to have content only accessible by screen reader. .is-focusable can be use as well so the content of this one will be visible on focus.
Example:
This text will only appear on focus :)
See more Extra text form screen reader only
<div class="has-p-3 has-bg-primary">
<a href="#" class="screen-reader-only is-focusable">This text will only appear on focus :)</a>
<p>See more<span class="screen-reader-only"> Extra text form screen reader only</span></p>
</div>