.wp-block-image.is-style-fade-top {
    margin-top: -100px;
    position: relative;
    z-index: -1;
}

.wp-block-image.is-style-fade-top::after {
    background-image: linear-gradient(to top, transparent 60%, white);
    bottom: 0;
    content: '';
    height: 100%;
    left: 0;
    position: absolute;
    width: 100%;
}