.sub ul {text-align:center;}
.sub ul li {background:#3978b3;display:inline-block;width:30%;margin:20px 10px;padding:30px 0 20px;}
.sub ul li span {display:block;font-size:16px;padding:10px 0;color:#fff;margin-top:10px;}

.sub ul li img{width: 100%;
    max-width: 46px;} 
/* tablet */
@media screen and (min-width:769px) and (max-width:991px){
}

/* mobile */
@media screen and (max-width:768px){
    .sub ul li {width:100%;margin:inherit;margin-bottom:20px;}
}