Give a background color ro gradient to your element.
Background color
Classes use for background color
<div class="p-3 mb-2 bg-primary text-white">.bg-primary</div>
<div class="p-3 mb-2 bg-secondary text-white">.bg-secondary</div>
<div class="p-3 mb-2 bg-success text-white">.bg-success</div>
<div class="p-3 mb-2 bg-danger text-white">.bg-danger</div>
<div class="p-3 mb-2 bg-warning text-dark">.bg-warning</div>
<div class="p-3 mb-2 bg-info text-dark">.bg-info</div>
<div class="p-3 mb-2 bg-light text-dark">.bg-light</div>
<div class="p-3 mb-2 bg-dark text-white">.bg-dark</div>
<div class="p-3 mb-2 bg-body text-dark">.bg-body</div>
<div class="p-3 mb-2 bg-white text-dark">.bg-white</div>
<div class="p-3 mb-2 bg-transparent text-dark">.bg-transparent</div>
Background gradient
Classes use for background gradient
<div class="p-3 mb-2 bg-primary bg-gradient text-white">.bg-primary.bg-gradient </div>
<div class="p-3 mb-2 bg-secondary bg-gradient text-white">.bg-secondary.bg-gradient </div>
<div class="p-3 mb-2 bg-success bg-gradient text-white">.bg-success.bg-gradient </div>
<div class="p-3 mb-2 bg-danger bg-gradient text-white">.bg-danger.bg-gradient </div>
<div class="p-3 mb-2 bg-warning bg-gradient text-dark">.bg-warning.bg-gradient </div>
<div class="p-3 mb-2 bg-info bg-gradient text-dark">.bg-info.bg-gradient </div>
<div class="p-3 mb-2 bg-light bg-gradient text-dark">.bg-light.bg-gradient </div>
<div class="p-3 mb-2 bg-dark bg-gradient text-white">.bg-dark.bg-gradient </div>