Margin underneath each link

This is a fairly simple request but I can’t for the life of me seem to figure out where to drop this. I was thinking of adding this piece of css to space out my links under each row: margin-bottom: 20px; but i do not know where to drop this.

Webpage is http://viaggiobybike.co.uk/acknowledgements/

Please let me know if anyone has nay suggestions.

Thank you

https://wordpress.org/plugins/link-library/