Flask-Project-Template/src/core/static/css/main.css

#bg {
    position: fixed;
    top: 0%;
    left: 0%;
    width: 100%;
    height: 100%;
    z-index: -999;
    object-fit: cover;
}

#bg img {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    width: 100%;
    height: 100%;
    z-index: -999;
}


/* Other message text colors */
.errorTxt   { color: rgb(170, 18, 18); }
.warningTxt { color: rgb(255, 168, 0); }
.successTxt { color: rgb(136, 204, 39); }