Interesting and discreet Tasks Buttons on the Panel in multiple colors ( white, purple, blue, green). Reduced transparency of the Panel as well as the start of the menu. This Thema, beautifully goes on dark and bright backgrounds. The complete theme is in Blue Details.
This theme will install as dependencies:
Plasma Theme "Crown Blue": Here
Plasma Color Scheme: "Crown Blue": Here
Aurorae Theme: "Crown Blue": Here
Icon Theme "Breeze Chameleon Dark": Here
The author of the wallpaper: charlie-henson: Here