by the way i need your support:
I should apply a different logo for a specific portfolio category, in which way I have to prooced?
could you give me the css code to add this info?

I try to use this one but it works only for the main pages not for the portfolio items:
.page-id-8068 .logo img {
content: url(http://www.tredigraph.it/wp-content/uploads/2017/12/logo_vr_2018-1.png);
}

thanks a lot