index/css/background.css

background {
    position: fixed;
    top: 0px;
    height: 100vh;
    z-index: 1;
}

@media screen and (max-width:1000px) {
    background {
        left: -241px;
        width: 200%;
        background-size: auto 100%;
        background-position: 10%;
    }
}

@media screen and (min-width:1000px) {
    background {
        left: -100px;
        width: 120%;
        background-size: 85% auto;
        background-position: 40%;
    }
}

background {
    transition: all 700ms ease-out;

    background-image: url(../bg.jpg);
    background-repeat: no-repeat;
}

.about>background {
    height: 100px;
    background-size: auto auto !important;
}