how to make invisible the file input field?

Capturar.PNG

I want to take everywhere in red, leaving only the part marked in yellow.

Below is my code:

Code:

Ext.define('ExtMVC.view.ImageUpload',{
        extend: 'Ext.window.Window',
        alias: 'widget.imageupload',
        width: 500,
    frame: true,
    title: 'Adicionar imagem',
    autoShow: true,
    modal: true,




    defaults: {
        anchor: '100%',
        allowBlank: false,
        msgTarget: 'side',
        labelWidth: 50
    },


    items: [
        {
                xtype: 'form',
                itemId: 'imageForm',
                bodyPadding: '10',
                items: [
                {
                        xtype: 'filefield',
                        fieldLabel: 'Imagem',
                    emptyText: 'Selecione uma imagem',
                    name: 'arquivo',
                    buttonText: '',
                        buttonConfig: {
                                iconCls: 'icon-image'
                        }
                }
            ]
        }
    ],


    dockedItems: [
        {
            xtype: 'toolbar',
            dock: 'bottom',
            layout: {
                xtype: 'hbox',
                pack: 'end'
            },
            items: [
                {
                    xtype: 'button',
                    text: 'Salvar',
                    itemId: 'save',
                    iconCls: 'icon-save'
                },
                {
                    xtype: 'button',
                    text: 'Cancelar',
                    itemId: 'cancel',
                    iconCls: 'icon-reset'
                }
            ]
        }
    ]
    
});

Thank you in advance.



how to make invisible the file input field?