:medium pseudo element?

Can anyone shed light on what the “:medium” pseudo element is? It appears after all CSS selectors in my site. Here’s an example:

   .section {
      position: relative;
      padding-top: 80px;
      padding-right: 10px;
      padding-bottom: 80px;
      padding-left: 10px;
      background-color: white;
      text-align: center;
    }

    .section:medium {
      margin-top: 16px;
      margin-bottom: 16px;
      padding-top: 0px;
      padding-bottom: 0px;
    }

Here is my site Read-Only: LINK
(how to share your site Read-Only link)

See this post → New CSS Preview - Community resources / General - Forum | Webflow and look for a response by me.

Oh - of course! cool thanks.