title: CSS in Bootstrap 4 ''Mask''
body: <p>There is the use of &quot;Mask&quot; in Bootstrap 4 or 5. How can I do this in CSS? Adding background color and z-index to an image does not accept it.</p>
  <p><a href="https://mdbootstrap.com/docs/standard/content-styles/masks/" rel="nofollow noreferrer">https://mdbootstrap.com/docs/standard/content-styles/masks/</a></p>