@media (min-width: 700px) {
    .Imagen1 {
        content: url("../DECHRAbig.jpg");
    }

    .Imagen2 {
        content: url("../WALTHAMbig.jpg");
    }

    .Imagen3 {
        content: url("../VETOQUINOLbig.jpg");
    }

    .Imagen4 {
        content: url("../AMMVEPEbig.jpg");
    }

    .Imagen5 {
        content: url("../MARSbig.jpg");
    }

    .Imagen6 {
        content: url("../LAVECCSbig.jpg");
    }
}

@media (max-width: 700px) {
    .Imagen1 {
        content: url("../DECHRAsmall.jpg");
    }

    .Imagen2 {
        content: url("../WALTHAMsmall.jpg");
    }

    .Imagen3 {
        content: url("../VETOQUINOLsmall.jpg");
    }

    .Imagen4 {
        content: url("../AMMVEPEsmall.jpg");
    }

    .Imagen5 {
        content: url("../MARSsmall.jpg");
    }

    .Imagen6 {
        content: url("../LAVECCSsmall.jpg");
    }
}