Number of images in Gallery Reel

To add number of images in Gallery Reel Squarespace, you can follow these steps.
First, find Reel ID.

Next, use CSS code like this

section[data-section-id="62309c7df0e62e3ac884c504"] {
.gallery-reel-list {
    counter-reset: css-counter 0;
    list-style-type: none;
}
figure.gallery-reel-item{
    counter-increment: css-counter 1;
}
figure.gallery-reel-item::before {
    content: counter(css-counter) '/12';
    position: absolute;
    bottom: 0;
    font-size: 20px;
    left: 20px;
    color: black;
}}

Result