html, body {
    height: 100%;
   
}

.cen {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
}

.allow {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    background-color:#0f6a39;
    height: 300px;
    width: 400px;
    color: yellow;
    border: 20px outset #07169d;
    border-radius: 20px;
    font-size: 20px;
    font-weight: bold;
    padding: 20px;
    
}