How to add padding on Masonry Caption

To add padding on Masonry Caption, you can use these CSS code to Website Tools > Custom CSS.
#1. All Masonry Captions (Desktop)

@media screen and (min-width:768px) {
figcaption.gallery-caption.gallery-caption-grid-masonry {
    padding-left: 50px;
    padding-right: 50px;
    width: calc(~"100% - 100px");
}
}

#2. All Masonry Captions (Mobile)

@media screen and (max-width:767px) {
figcaption.gallery-caption.gallery-caption-grid-masonry {
    padding-left: 10px;
    padding-right: 10px;
    width: calc(~"100% - 20px");
}
}

#3. Specific Masonry (Desktop)
First, you need to find Masonry Gallery ID.
Next, use CSS code like this

@media screen and (min-width:768px) {
section[data-section-id="66d426c1fb5aaa778bed4721"] figcaption.gallery-caption.gallery-caption-grid-masonry {
    padding-left: 50px;
    padding-right: 50px;
    width: calc(~"100% - 100px");
}
}

#4. Specific Masonry (Mobile)
Similar #3, find ID, then use CSS code like this

@media screen and (max-width:767px) {
section[data-section-id="66d426c1fb5aaa778bed4721"] figcaption.gallery-caption.gallery-caption-grid-masonry {
    padding-left: 10px;
    padding-right: 10px;
    width: calc(~"100% - 20px");
}
}