JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" type="text/css" href="//cdn.sencha.io/ext-4.1.0-gpl/resources/css/ext-all-debug.css"
/>

CSS

.list-item{
    background: yellow;
}

JavaScript

Ext.define("State", {
    extend: 'Ext.data.Model',
    
    fields: [
        {type: 'string', name: 'fips_state_code'},
        {type: 'string', name: 'state_name'}
    ]
});


Ext.create('Ext.data.Store', {
  storeId:'States',
  model: 'State',
  data: [{'fips_state_code': '0', 'state_name': ' Alabama '}]
});

Ext.create('Ext.form.field.ComboBox', {
    fieldLabel: 'Choose State',
    store: Ext.getStore('States'),
    queryMode: 'local',
    valueField: 'fips_state_code',
    displayField: 'state_name',
    listConfig: {
    // Custom rendering template for each item
                getInnerTpl: function() {
                    return '<div class="list-item">{state_name} ({state_name})&nbsp;<\/div>';
                }
            },
    renderTo: Ext.getBody()
});