/*Give a  #container the height of the window*/
#container {    
    height: 100vh;
}

/*Put this element in the center of the  #container*/ 
#content{
    position: relative;
    top: calc(50% - 250px);    
    left: calc(50% - 250px);   
    display: flex;
    justify-content: center;
    align-items: center;
}

.login #content-main{
    position: static;
    margin-left: revert;
    margin-top: revert;
}