Qt5ct

From wikinotes

Qt5 attempts to match settings from current desktop environment.
qt5ct lets you set deskto-environment agnostic overrides.

Documentation

man qt5ct https://manpages.ubuntu.com/manpages/bionic/man1/qt5ct.1.html
repo https://sourceforge.net/projects/qt5ct/

Locations

~/.config/qt5ct/qt5ct.conf user config
~/.config/qt5ct/qss/*.qss user qss stylesheets for UI
/usr/share/qt5ct/qss/*.qss installed qss stylesheets referenced in UI

Enable

export QT_QPA_PLATFORMTHEME=qt5ct

Configuration

Stylesheet Overrides

Add your own stylesheet overrides to ~/.config/qt5ct/qss/*.qss.
Enable your overrides in ~/.config/qt5ct/qt5ct.conf under [Interface]stylesheets.

See Python qt: colours/stylesheets for syntax.

/* ~/.config/qt5ct/qss/*.qss */

QSlider::groove:horizontal {
    border: 1px solid palette(mid);
    background: palette(alternate-window);
    height: 10px;
    border-radius: 3px;
}
QSlider::groove:vertical {
    border: 1px solid palette(mid);
    background: palette(alternate-window);
    width: 10px;
    border-radius: 3px;
}
# ~/.config/qt5ct/qt5ct.conf

[Interface]
stylesheets=/usr/share/qt5ct/qss/sliders-simple.qss, /usr/share/qt5ct/qss/tooltip-simple.qss