body {
    position: relative;
}

body::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('../img/main-bg.png') no-repeat fixed;
    -webkit-background-size: cover;
    background-size: cover;
    opacity: 0.5; /* Adjust opacity here, 1 is fully opaque and 0 is fully transparent */
    z-index: -1; /* Ensure the image stays behind the content */
}