STYLE.css

QMainWindow {
    border: 1px solid black;
    background-color: COLOR1;
}

QListWidget {
    background-color: COLOR1;
}

TabWidget, QListWidget {
    border: none;
}

    TabWidget::pane {
        border: 0;
    }

    TabWidget#main_tab_widget QTabBar::tab:selected {
        color: #ff0000;
        background-color: COLOR1;
        border-radius: 5px;
        width: 90px;
        height: 30px;
    }

    TabWidget#main_tab_widget QTabBar::tab:!selected {
        background-color: COLOR2;
        border-radius: 5px;
        width: 80px;
        height: 30px;
    }

QPushButton, PushButtonWithId, QLineEdit {
    border-radius: 10px;
    background-color: COLOR2;
}

* {
    color: rgb(200, 200, 200);
}

QSpinBox {
    background-color: COLOR2;
    color: rgb(200, 200, 200);
    border: none;
}

QLabel#word_page_picture_label {
    border-radius: 10px;
}

QMessageBox {
    background-color: COLOR1;
    color: white;
}