.post-notification-image img, 
.post img {
    width: 70% !important;
    max-width: 100% !important;
    height: auto !important;
    display: block !important;
}

@media only screen and (max-width: 480px) {
    .post-notification-image img, 
    .post img {
        width: 100% !important;
    }
}