You can update the background color of the highlight border which is defined on ::after pseudo selector when hovering the .hightlight selector using .hightlight:hover::after as follows.
.highlight {
position: relative;
}
.highlight::after {
content: " ";
left: 0;
right: 0;
position: absolute;
bottom: 1px;
height: 6px;
background-color: #9bffb0a6;
z-index: -1;
}
.highlight:hover::after {
background-color: #4dff73;
}<div><span class="highlight">Text</span>Another Text</div>CLICK HERE to find out more related problems solutions.