Thank you very much cgscomputers, but unfortunately I was not using a child theme. I tried anyway to create it and to do as you did but neither worked 🙁
@btmaster I think you took the wrong topic!
Problem is the site is still under construction so it can’t be let to be public, so I’m covering it with a Coming Soon page. Anyway, it is http://www.alessandrogerosa.it.
I’ll try to explain it more clearly: Hestia theme visualize a navbar, in which there is the title of the website at left and optional menu at right.
The navbar is builded to be trasparent when at the top of the page, and to become white when scrolling down on the frontpage.
My problem is actually that if I scroll the page in preview mode the navbar becomes white and is all ok, but in the real website if I scroll the frontpage the navbar stays trasparent not changing to white background color.
I also tried to delete and re-install the theme, but nothing happened.
Thank you another time
