Content-type icon for custom types in Plone 5 toolbar?

[zopyx (Andreas Jung)]

How can you add an icon to a custom portal type ("Connector" here)?
Interesting that the inspector does not show me anything for the :before rule of a core Plone content type

-aj

[espenmn (Espen)]

Why should there be anything for ::before ?
The other actions put the icon on ::after, something like:

a#name-of-action::after {
  font-family: "Fontello";
  content: '\e808';
  left: 0;
  position: absolute;
}