html, body {
    height: 100%;
}

.flex-box {
    height: 100%;
    display: flex;
    flex-flow: row nowrap;
    align-content: center;
    align-items: center;
    justify-content: center;
}

.flex-box-content {
    display: inline;
}

.btlogin {
    margin-top: 0.8em;
}