Hello David,
I am really sorry for the delay of this reply as it is a weekend for us here. Can I know which extension are you referring to here? Also, if you could provide us with the link to the page that you are referring to, it would be awesome.
Ideally, you shouldn't be making changes on the css because when you upgrade EasySocial, you will need to re-apply the hacks again. Instead, if your Joomla template supports a custom.css, you could just add custom css rules in the custom.css file.