hover css bootstrap code example

Example 1: on hover css

/* Changes an element's color on hover */

.selector {
	background-color: black;
}

.selector:hover {
	background-color: blue;
}

Example 2: bootstrap 4 class for hover

<div class="view overlay">
    <img src="https://mdbootstrap.com/img/Photos/Horizontal/City/6-col/img%20(3).jpg" class="img-fluid " alt="">
     <div class="mask rgba-red-strong">

    </div>
</div>