Caption boxes are too big

By examining the code I find that the caption box margin size (bottom-margin) is defined by the margin size for by the subtitle part of the stylesheet. This is the coding for it. So if I change it to 0, it fixes my image caption box but every paragraph then loses its margin.

}
.sub-title { font-size: 12px }
p { margin-bottom: 20px }
a {
    text-decoration: none;
    color: #4A8CF7;
    -webkit-transition: background-color, color 0.2s linear;
    -moz-transition: background-color, color 0.2s linear;
    transition: background-color, color 0.2s linear;
}

Example of what it does to my imag here: https://animalcarebasics.com/siamese-kittens-born-white/