Rounded corners

https://www.yphix.com/projects
https://www.yphix.com/blog

Is there somebody who can help me to give the images on the summary pages rounded corners?

I've added this code but it's not working:

.sqs-block-summary-v2 .summary-thumbnail {
  border-radius:15px;
}

Many thanks!

Thank you so much! I've found te code in the article!