css parallax

/* HEADER */
html {
    height: 100%;
    overflow: hidden;
}
body {
    background: #414449;
    margin: 0;
    padding: 0;
    perspective: 1px;
    transform-style: preserve-3d;
    height: 100%;
    overflow-y: scroll;
    overflow-x: hidden;
}
header {
    color: #fff;
    box-sizing: border-box;
    min-height: 100vh;
    padding: 30vw 0 5vw;
    position: relative;
    transform-style: inherit;
    width: 100vw;
    font-family: "MS GOTHIC";
    font-size: 2.5vh;
}

header h1 {
    margin-top: -100px;
}

header, header:before {
    background: 50% 50% / cover;
}

header::before {
    bottom: 0;
    content: "";
    left: 0;
    position: absolute;
    right: 0;
    top: 0;
    display: block;
    background-image: url(background.jpg);
    background-size: cover;
    transform-origin: center center 0;
    transform: translateZ(-1px) scale(2);
    z-index: -1;
    min-height: 100vh;
}

header * {
    font-weight: normal;
    letter-spacing: 0.2em;                  /* odstęp między literami całego headera */
    text-align: center;                     /* wycentrowanie całego headera */
}
/* HEADER END */