Conditional header text based on group membership

I’ve done a lot of experimentation and right now this is working, but I do have a question.

In Header:

<div id='renew' class='renewlink' align="center">
    <a href="https://www.example.com/renewlink" target="_blank")
    <font color='red'>
    Please click to renew your membership
    </font>
    </a>
</div>

In CSS:

.renewlink{
    display: none;
  }

.primary-group-renewal .renewlink{
    display: block;
  }

I really expected this to work instead of the double CSS entry above and it did not. What am I missing here?

:not(.primary-group-renewal) .renewlink{
    display: block;
  }

Thanks