A new application is available for Sparkers: Qt5ct.

This utility allows users to configure Qt5 settings (theme, font, icons, etc.) under DE/WM without Qt integration.

Qt5ct could use qt5 gtk theme, KDE breeze theme, the fusion theme, QtCurve theme and many more. Each style could be customized further by changing the color schema.

Installation via Synaptic or APT:
sudo apt update
sudo apt install qt5ct

Then reboot.

Qt5ct