@media all and (max-width: 599px){

    .efect_hover_1 .a {
        width:400px;
        height:266px;
        overflow:hidden;
        background-image:url('../img/dat-1.jpg');

        box-shadow:0 0 10px 1px #ddd;
    }
    .efect_hover_1 .b {
        width:0;
        height:266px;
        overflow:hidden;

        transform:skew(-20deg);
        transition:width 1s ease;
    }
    .efect_hover_1 .a:hover .b {
        width:400px;

    }
    .efect_hover_1 .c {
        width:400px;
        height:266px;
        transform:skew(20deg);

        background-image:url('../img/dat-2.jpg');
        background-position:0 0;
    }
}

@media all and (min-width: 599px){

    .efect_hover_1 .a {
        width:800px;
        height:533px;
        overflow:hidden;
        background-image:url('../img/dat-1.jpg');

        box-shadow:0 0 10px 1px #ddd;
    }
    .efect_hover_1 .b {
        width:0;
        height:533px;
        overflow:hidden;

        transform:skew(-20deg);
        transition:width 1s ease;
    }
    .efect_hover_1 .a:hover .b {
        width:800px;
    }
    .efect_hover_1 .c {
        width:800px;
        height:533px;
        transform:skew(20deg);

        background-image:url('../img/dat-2.jpg');
        background-position:0 0;
    }
}