¿Cómo ocultar un botón ( icono SVG) si el usuario ha iniciado sesión?

[omarfilip]

Ah, lo siento, querías lo contrario, así que: 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.