sencha touch modern developer mobile terminal, textfield display exception

Question

The development of the mobile terminal landing interface, the runtime found that the text input box display abnormal. If you put the code in toolbar to show no problem, the house ah formPanel shows weird, the effect is as follows enter image description here

mycode：

Ext.define('GasApp.view.main.login.Login',{
    extend : 'Ext.form.Panel',
    xtype : 'loginView',
    requires: [
        'Ext.field.Password',
        'Ext.Button',
        'Ext.field.Toggle',
        'Ext.layout.HBox',
        'Ext.Toast',
        'GasApp.view.main.login.Controller'
    ],
    alternateClassName: 'loginView',
    controller : 'loginCtrl',
    listeners: {
        initialize: 'onLoginInitialize'
    },
    config:{
        padding: '40 30 0 30',
        items: [{
            xtype: 'textfield',
            name: 'account',
            ui : 'text_',
            label: '账号',
            clearIcon:true,
            required: true
        },{
            xtype: 'passwordfield',
            name: 'password',
            label: '密码',
            required: true
        },{
            items: [{
                xtype: 'togglefield',
                name: 'persist',
                label: '记住我',
                labelTextAlign: 'right',
                labelAlign: 'left',
                value: true
            }]
        },{
            xtype: 'button',
            width: '100%',
            text: '登   陆',
            ui: 'action',
            listeners: {
                tap: 'onLoginClick'
            }
        }]
    }
});