blur and transparent background in a div css

    .bgblur {
        border-radius: 15px;
        background: hsla(0, 0%, 100%, .55);
        box-shadow: 4px 4px 20px 0 rgba(0, 0, 0, .25);
        -webkit-backdrop-filter: blur(4px);
        backdrop-filter: blur(4px);
    }        


details[open]:before {
    content: "";
    -webkit-backdrop-filter: grayscale(.7)blur(3px);
    backdrop-filter: grayscale(.7)blur(3px);
    z-index: 9998;
    background: #0000004d;
    width: 100%;
    height: 100%;
    position: fixed;
    top: 0;
    left: 0;
}