Hi Nikko,
sorry but the css did not do the job.
I tried myself and found a not so elegant solution:

#top .av-caption-style-overlay .av-masonry-item-with-image .av-inner-masonry-content {
    background: rgba(255,255,255,0.50);
}
#top .av-caption-style-overlay .av-masonry-item-with-image .av-inner-masonry-content *, #top .av-caption-style-overlay .av-masonry-item-with-image ins::before, #top #wrap_all .av-caption-style-overlay .av-masonry-item-with-image del {
    color: #000;
}

Maybe there is a better solution….. but this one works.
Best regards,
Iska