JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://dev.sencha.com/deploy/ext-4.0.0/resources/css/ext-all.css">

JavaScript

var win = Ext.create('widget.window', {
    title: 'Layout Window',
    closable: true,
    closeAction: 'hide',
    width: 750,
    height: 500,
    layout: 'fit',
    animCollapse: true,
    bodyPadding: 5,
    items: [{
        xtype: 'container',
        layout: 'column',
        items: [{
            xtype: 'fieldset',
            columnWidth: '0.5',
            style: 'margin-right: 5px',
            title: 'Details',
            layout: 'anchor',
            items: [{
                xtype: 'displayfield',
                fieldLabel: 'Name',
                name: 'customer_name',
                id: 'customer_name',
                width: 300
            }, {
                xtype: 'displayfield',
                fieldLabel: 'ID Card',
                id: 'customer_id',
                name: 'customer_id',
                width: 300
            }, {
                xtype: 'displayfield',
                fieldLabel: 'Address',
                name: 'address',
                id: 'address',
                width: 300
            }]
        }, {
            xtype: 'fieldset',
            columnWidth: '0.5',
            title: 'Details',
            layout: 'anchor',
            autoHeight: true,
            items: [{
                xtype: 'textfield',
                labelWidth: 120,
                fieldLabel: 'invoice',
                anchor: '98%',
                name: 'invoice_number',
                id: 'invoice_number',
                allowBlank: false,
                readOnly: true
            }, {
                xtype: 'textfield',
                labelWidth: 120,
                fieldLabel: 'Payment Amount',
                anchor: '98%',
                name: 'payment_amount',
                id: 'payment_amount',
                allowBlank: false
            }, {
                xtype: 'button',
                id: 'test',
                text: 'test',
                handler: function () {
                   ...