Java Scene Builder Menu item size

I am coding a java project and I have started programming from User Interface. I am using Java Scene builder to design the forms. It automatically creates the fxml file and imports to Eclipse. The Problem is; When I add a MenuButton and try to add menuitems, i can not give a text width or size to items. My Code looks like;

                        <items>
                            <MenuItem mnemonicParsing="false" style="width: 221px;" text="Envanter Ekle" textSize="200sp" />
                            <MenuItem mnemonicParsing="false" text="Envanter Sorgulama" />
                              <MenuItem mnemonicParsing="false" text="Envanter Raporlama" />
                          </items>

I have tried giving width property but it didnt work.. Can anyone please help ? Thanks in advance