html, body {
    margin: 0;
    padding: 0;
    background: #FFF;
}

.main {
    margin-left: auto;
    margin-right: auto;
    width: 30%;
    padding-top: 25vh;
}

.main img {
    width: 100%;
    height: auto;
}

@media only screen and (max-width: 600px) {
    .main {
        width: 50%;
    }
}