.issuu {width:48%;margin-left:3%;height:500px;box-sizing:border-box;-moz-box-sizing:border-box;}
.issuu:first-child {margin-left:0;}

@media screen and (max-width: 830px) { 
.issuu {height:500px;}
}

@media screen and (max-width: 760px) { 
.issuu {width:100%;margin-left:0;height:500px;}
}