In react-masonry, how to get vertical spacing? margin-bottom is not working for me

Question

The 'gutter' property works fine, but as you can see in columns 2 and 3, margin-bottom styles don't have any effect.

All the divs are position: absolute.

What to do? I tried faking the effect with thick borders, color: transparent, but not working so far.

.announcement {
    background: rgba(255,255,255,.7);
    outline: 10px solid transparent; // <--- comes out white instead of
    box-sizing: border-box;                  showing the blue background
    width: 450px !important;
    padding: 10px;

    img {
        max-width: 100% !important;
    }

}