@media only screen and (max-width:960px)
{
    div a {width: 25%; padding: 15px;}
}

@media only screen and (max-width:768px)
{
    div a {width: 27%; padding: 15px 10px;}
}

@media only screen, (max-width:769px) and (max-width:959px)
{
    div a {padding: 10px 21px 19px 10px;}
}