.bg {
    background: url('/static/picture/main.jpg') no-repeat;
    background-color: #EDCEF3;
    background-size: cover;
    background-position: 50% 0px;
    width: 100vw;
    height: 100vh;
    position: fixed;
    left: 0px;
    top: 0px;
    z-index: -100;
}  

.monospace { 
    font-family: monospace; 
}