Theming and Styling
You will have noticed by now that the UI components in Ext JS 4 have a common look and feel. The UI components appear with a tinge of light blue in color, by default. The buttons, panels, toolbars, grids, and so on have a uniform appearance. In our applications we may have to customize the appearance of these components. In a traditional UI-based application, this involves modifying the stylesheets of the components. You identify the CSS classes and id(s) of the UI components and start making changes to them.
Customizing the look and feel of the components by modifying their CSS properties, one by one, is an uphill ...