div.gallery {
    border: 1px solid #ccc;padding:2px;
}

div.gallery:hover {
    border: 1px solid #777;opacity:0.7;
}

div.gallery img {
    width: 100%;
    height: auto;
}



*{
    box-sizing: border-box;
}

.responsive {
    padding: 0 0;
    float: left;
    width: ;
}



.clearfix:after {
    content: "";
    display: table;
    clear: both;
}