.projprev {
    position: fixed;
    left: calc(50vw - 100vh/2 - 200px - 3em + 115vh);
    top:0;
    width:27.5em;
    height:100vh;
    background-color: rgb(20,20,20);
    border-right: 0.5em solid black;
}
.projprev-iframe {
    width: 100%;
    height: 16.5em;
    border: 0.1em solid white;
}