Install kwin-style-breeze by entering the following commands in the terminal:
sudo apt update sudo apt install kwin-style-breeze
Description:
KWin Breeze Style
This is the Breeze window manager style for the KDE Plasma 5 desktop. . This package is part of the Breeze theme module.
Homepage: https://projects.kde.org/projects/kde/workspace/breeze
Version: 4:5.12.4-0ubuntu1
Section: universe/kde