mirror-chatterino2/resources/qss/settings.qss

#tabWidget {
    background-color: #333;
}

* {
    font-size: <font-size>px;
}

SettingsDialogTab:hover {
    border: 1px solid grey;
}

QLabel, QCheckBox, QGroupBox, SettingsDialogTab {
    color: white;
}

QGroupBox {
    background-color: #444;
}

QCheckBox::indicator {
    width: <checkbox-size>px;
    height: <checkbox-size>px;
}