Comment masquer un bouton (icône SVG) si l'utilisateur est connecté ?

[omarfilip]

Ah, désolé - vous vouliez l’inverse, donc : not(.anon)

How to display a banner for visitors only?

You can make use of the anon class added to the <body> tag. More on this here: The selector in your case would be inverted like so: body:not(.anon) { #banner { display: none; } } Which effectively hides the banner unless the user is logged out.