How to make Top Panel and Dock completely transparent? (Ubuntu 18.04)

Question

I want to make the GNOME top panel and dock completely transparent so that desktop wallpaper is completely visible.

I already created my own theme and added the following css rules. My top panel turned transparent but there is still some kind of gradient from the bottom. In addition I cant get to work the dock transparency. Instead of transparent it gets black.

@import url("/usr/share/gnome-shell/theme/ubuntu.css");  

#panel {
  background-color: rgba(0,0,0,0);
}

#dash {
  background-color: rgba(0,0,0,0);
}

#dash .placeholder {
  background-image: none;
}