QTCurve theme for KDE Desktops mimicking the Windows 10 GUI (as close as QTCurve let me go)
to install this theme, open a terminal and type :
sudo apt-get install qtcurve
then, head to Settings > Application Appearance > Style and in the drop-down menu select QTCurve. Then, click Configure and import the .qtcurve file. Apply changes and youre done!
To apply the window decoration, head to Settings > Workspace Appearance > Window Decoration and select the QtCurve theme in the list.