.blur {
    display: none;
}

.blur.visible {
    display: block;
    background: rgba(0, 0, 0, 0.75);
    /* backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px); */
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 99;
}