Create a leave dialog theme according to the mockup and these specifications:
https://share.kde.org/index.php/s/YojnHEhf6qUmHLu
When a user press shutdown, lock and logout the desktop fades, darkens, and an
overlay black at 70% opacity pops up the logout options are displayed with the
one the user selected preselected and in the center, from there the user can
use mouse or arrows to move to another option, like go from the shutdown to
reboot. The selected option is fully opaque and white (#ffffff) and the not
selected options are at 60% opacity and light grey (#eff0f1)