.marcass {
    float: left;
    height: 190px;
    margin: 20px 2.5% 0;
    width: 20%;
}
.marcass > img {
    float: left;
    width: 100%;
}
@media only screen and (max-width: 550px) {
	.marcass {
		width: 45%;
	}
}
@media only screen and (max-width: 350px) {
	.marcass {
		width: 100%;
		margin: 10px 0 0;
	}
}