스크롤링 Blur 스타일

.blur {
    position: relative;
    -webkit-user-select: none;
    -moz-user-select: none;
    user-select: none;
    pointer-events: none;
    --h: min(96px,var(--page-top));
    position: sticky;
    width: calc(100% + var(--body-margin-left) + var(--body-margin-right));
    margin-left: calc(-1 * var(--body-margin-left));
    height: var(--h);
    z-index: 1;
    -webkit-backdrop-filter: blur(5px);
    backdrop-filter: blur(5px);
    opacity: .95;
    -webkit-mask-image: linear-gradient(var(--direction),var(--mask-visible) 25%,var(--mask-hidden));
    mask-image: linear-gradient(var(--direction),var(--mask-visible) 25%,var(--mask-hidden))
}

.blur:after {
    content: "";
    position: absolute;
    inset: 0;
    background: linear-gradient(var(--direction),var(--bg),var(--transparent))
}

.blur:first-child {
    margin-bottom: calc(-1 * var(--h));
    top: 0;
    --direction: to bottom
}

.blur:last-child {
    margin-top: calc(-1 * var(--h));
    bottom: 0;
    --direction: to top
}