Now with a little bit of magic, we can customize that background.

If you only have one modal in your page, you can simply use that class .oxy-modal-backdrop to style it.

.oxy-modal-backdrop {
background-image: linear-gradient(0deg, rgba(255,255,255,0) 25%, #000000 25%, #000000 50%, rgba(255,255,255,0) 50%, rgba(255,255,255,0) 75%, #000000 75%, #000000 100%);
background-size: 8.00px 8.00px;
}

If you have several modals in the same page (just like this current page), and you want to have different backdrop styles for each of them, you will have to add a data attribute, just like this example:

.oxy-modal-backdrop[data-trigger-selector="#fancy_icon-40-635"] {
background-image: linear-gradient(135deg, rgba(255,255,255,0) 25%, #000000 25%, #000000 50%, rgba(255,255,255,0) 50%, rgba(255,255,255,0) 75%, #000000 75%, #000000 100%);
background-size: 11.31px 11.31px;
}