ul.product-cats li {
    list-style: none;
    margin-left: 0;
    margin-bottom: 4.236em;
    text-align: center;
    position: relative;
}
ul.product-cats li img {
       margin: 0 auto;
       background : white ; 
}
hr {
     color: #000;
     background: #000; 
     width: 75%; 
     height: 5px;
}
 
@media (min-width:768px){
 ul.product-cats {
        margin-left: 0;
        clear: both;
    }
 ul.product-cats li {
         height: 300px;
        width: 29.4117647059%;
        float: left;
background : #ececec ;
        margin-right: 2.8823529412%;
    }
ul.product-cats hr {
     color: #f00;
     background: #f00; 
     width: 75%; 
     height: 5px;
    }
     
}