QFD2/QFluentWidgets/qss/dark/combo_box.qss

ComboBox {
    border: 1px solid rgba(255, 255, 255, 24);
    border-radius: 5px;
    border-bottom: 1px solid rgba(255, 255, 255, 17);
    padding: 5px 31px 6px 11px;
    font: 14px 'Segoe UI', 'Microsoft YaHei';
    color: white;
    background-color: rgb(62, 63, 62);
    text-align: left;
}

ComboBox:hover {
    background-color: rgb(67, 68, 67);
}

ComboBox:pressed {
    background-color: rgb(56, 56, 56);
    border-bottom: 1px solid rgba(255, 255, 255, 24);
    color: rgba(255, 255, 255, 0.63);
}


ComboBoxMenu>MenuActionListWidget {
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 9px;
    background-color: rgb(43, 43, 43);
    outline: none;
    font: 14px 'Segoe UI', 'Microsoft YaHei';
}

ComboBoxMenu>MenuActionListWidget::item {
    margin-top: 4px;
    padding-left: 10px;
    padding-right: 10px;
    border-radius: 5px;
    border: none;
    color: white;
}

ComboBoxMenu>MenuActionListWidget::disbled {
    padding-left: 10px;
    padding-right: 10px;
    border-radius: 5px;
    border: none;
    color: white;
}

ComboBoxMenu>MenuActionListWidget::item:hover {
    background-color: rgba(255, 255, 255, 0.08);
}

ComboBoxMenu>MenuActionListWidget::item:selected {
    background-color: rgba(255, 255, 255, 0.08);
    color: white;
}

ComboBoxMenu>MenuActionListWidget::item:selected:active {
    background-color: rgba(255, 255, 255, 0.06);
    color: rgba(255, 255, 255, 0.7);
}