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>Test</title>
    </head>
    <body>
    </body>
</html>

CSS

.legendFieldSet {
    border-width: 0px; 
    margin-bottom:10px;
}

.legendFieldSet .x-tool-toggle{
    background-position: 0 -255px !important; /*the minus sign*/
}

.legendFieldSet .x-panel-collapsed .x-tool-toggle{
    background-position: 0 -240px !important; /*the plus sign*/
}

JavaScript

var form = new Ext.FormPanel({
    title: 'Simple Form with FieldSets',
    labelWidth: 75, // label settings here cascade unless overridden
    url: 'save-form.php',
    frame:true,
    bodyStyle:'padding:5px 5px 0',
    width: 700,
    renderTo: document.body,
    layout:'column', // arrange items in columns
    defaults: {      // defaults applied to items
        layout: 'form',
        border: false,
        bodyStyle: 'padding:4px'
    },
    items: [{
        // Fieldset in Column 1
        xtype:'fieldset',
        columnWidth: 0.5,
        title: 'Fieldset 1',
        collapsible: true,
        autoHeight:true,
        defaults: {
            anchor: '-20' // leave room for error icon
        },
        defaultType: 'textfield',
        items :[{
                fieldLabel: 'Field 1'
            }, {
                fieldLabel: 'Field 2'
            }, {
                fieldLabel: 'Field 3'
            }
        ]
    },{
        // Fieldset in Column 2 - Panel inside
        xtype:'fieldset',
        title: 'Show Panel', // title, header, or checkboxToggle creates fieldset header
        autoHeight:true,
        columnWidth: 0.5,
        checkboxToggle: true,
        collapsed: true, // fieldset initially collapsed
        layout:'anchor',
        items :[{
            xtype: 'panel',
            anchor: '100%',
            title: 'Panel inside a fieldset',
            frame: true,
            height: 100
        }]
    }]
});