.homeBlock {
    margin: 0 auto;
    max-width: 800px;
    text-align: center;
}
.homeBlock img {
    width: 40%;
    max-width: 300px;
    margin: 10px;
}

@media only screen and (max-width: 500px) {
    .homeBlock img {
        width: 100%;
        max-width: 500px;
        margin: 5px 0;
    }
}