Use this suite of background-color utilities to directly style elements.
<div class="center p1 bg-darken-1">.bg-darken-1</div>
<div class="center p1 bg-darken-2">.bg-darken-2</div>
<div class="center p1 bg-darken-3">.bg-darken-3</div>
<div class="center p1 bg-darken-4">.bg-darken-4</div>