Allow it maybe, but nothing happens. It stay at some 30vh. If I set it higher than 30vh, it become larger, but never lower.
I found the following code in /templates/css/cover.css 

.bx-cover {
    position: relative;
    z-index: 2;
    display: -webkit-flex;
    display: flex;
    -webkit-align-items: center;
    align-items: center;
    min-height: 40vh;
    text-align: center;
}

But even changing the minimum height does not have any effect.