¿Puedo tener por defecto una barra lateral oculta?

[hiddenseal]

Esto es algo similar, ya que la barra lateral parece estar controlada por el atributo aria-expanded

Way to default aria-expanded true for quoted internal links?

I’d like to show the content of a quoted post (link) by default The expand arrow is a bit too subtle. What methods do I have available to do this? Thanks [quote post]