Display Header HTML to only Logged in Users

[omarfilip]

Perhaps like this - wrap it in a div, i.e. logged_in_content and hide it from users who are not logged in:

html.anon div#logged_in_content {
  display: none;
}

as mentioned by @Falco:

Display banner topic only to logged in users?

Add the banner topic and hide it with CSS, the html.anon selector can hide it from non logged users.