.self-photo {
    display: block;
    margin: auto;
    width: 400px;
    height: 400px;
    border-radius: 50px;
    border-color: #30e3ca;
    border-width: 5px;
    border-style: solid;
}

@media (max-width: 450px) {
    .self-photo {
        width: 300px;
        height: 300px;
    }
}