Not reading child theme?

I’d like to change the margin between the events on the sidebar, so I identified the item using Chrome inspect element, and then copy and pasted the correct code (I think) into the child theme style – style.css. I changed 30px to 10px.

.tribe-events-list-widget ol li {
margin-bottom: 10px;
list-style: none;
}

However, when I save the code, and refresh the page, it has no effect. (when I change it in inspect element, it works great.)

Any ideas please?

Site is https://www.freyacat.co.uk/myctest

https://www.ads-software.com/plugins/the-events-calendar/