Hi. I wish I could change color of each panel individually. If I use Ubuntu layout (top panel for menu and indicators, and left panel for apps) - I want them to be different colors. Top panel - dark, left - light (translucient). Now - they just merging in one Г shaped panel, because there is no color separation between them.
See https://techbase.kde.org/Development/Tutorials/Plasma5/ThemeDetails#.22translucent.22_folder If you want to create different background for panels located at the top, bottom, left or right, then also create sets of background elements with the following prefixes: north, south, west and east respectively. For example the center element of the left positioned panel's background should be named west-center.