html, body{
    margin:0;
    padding:0;
    border:0;    
}

.background_layer {    
    background: blueviolet url('../images/universe.jpg');
    background-position: center;
    background-size: cover;
    height: 100vh;
    width: 100vw; 
    position: relative;
    z-index: 1;
}

.top_layer {    
    height: 100vh;
    width: 100vw; 
    position: absolute;
    top: 0;
    left: 0;
    z-index: 10;
}

.logo { 
    padding-top: 20px;  
    padding-bottom: 20px;  
    width: 200px;
    display: block;    
}

.center {
    margin-left: auto;
    margin-right: auto;
}