html {
    height: 100%;
}

body {
    background-color: #000000;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100%;
    padding: 0 15px;
    margin: 0;
}

.op {
    width: 400px;
    max-width: 90%;
}