header {
    position: relative;
    background: url("/imgs/bg.jpg") no-repeat center top;
    background-size: cover;
    background-attachment: fixed;
    background-position: center calc(40% - 20vh);
    background-repeat: no-repeat;
    height: 60vh;
    text-align: center;
    display: flex;
    justify-content: center;
    align-items: center;
}