You can use this code to Custom CSS box
/* Instagram Hover */
.slide a:before {
content: "";
background-color: rgba(255,255,255,0.75);
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
z-index: 9999;
opacity: 0;
transition: all 0.3s;
pointer-events: none;
}
/* caption hover */
.slide a:after {
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%,-50%);
color: white;
text-align: center;
z-index: 10000;
opacity: 0;
pointer-events: none;
content: "";
background-image: url(https://cdn-icons-png.flaticon.com/512/1384/1384031.png);
background-size: contain;
width: 30px;
height: 30px;
}
.slide:hover a:before, .slide:hover a:after {
opacity: 1;
}
Result
