JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://dev.sencha.com/deploy/ext-4.0.2a/resources/css/ext-all.css">
<html>
    <head>
        <title>ExtJS4 Test</title>
    </head>
    <body>
    </body>
</html>

JavaScript

// (FIXED) ExtJS Fieldset Buggy Resize in FF/Chrome (hbox layout)
//**************************//                        

Ext.onReady(function(){
    
    Ext.create('Ext.container.Viewport',{
        title: 'zz'
        , renderTo: Ext.getBody()
        , layout: 'fit'
        , items:
        [
            { 
                xtype: 'form'
                , autoScroll: true
                , layout: 'hbox'
                , items:
                [
                    {
                        xtype: 'container'
                        , flex: 1
                        , layout: 'anchor'
                        , defaults: { anchor: '100%' }
                        , items:
                        [
                            { 
                                xtype: 'fieldset'
                                , title: 'blah4'
                                , frame: false
                                , border: 0
                                , defaults: { anchor: '100%', msgTarget: 'under' }
                                , items:
                                [
                                    { xtype: 'textfield', fieldLabel: 'blah', value: 'zzz' }
                                    , { xtype: 'textfield', fieldLabel: 'blah', value: 'zzz' }
                                    , { xtype: 'textfield', fieldLabel: 'blah', value: 'zzz' }
                                    , { xtype: 'textfield', fieldLabel: 'blah', value: 'zzz' }
                                    , { xtype: 'textfield', fieldLabel: 'blah', value: 'zzz' }
                                    , { xtype: 'textfield', fieldLabel: 'blah', value: 'zzz' }
                                ]
                            }
                            , { 
                                xtype: 'fieldset'
                                , title: 'blah4'
                                , frame: false
                                , border: 0
                                , defaults: { anchor:...