The Kendo ThemeBuilder is a tool that lets you modify Kendo themes so that they match the look and feel of your site or app.
Because the ThemeBuilder is a browser bookmarklet, using it on your own pages is as easy as clicking a button. Just drag the ThemeBuilder button to your bookmarks bar, and voila! You can now load the theming interface on every page that contains Kendo components.
Since the ThemeBuilder can output LESS or CSS text, you need to perform a few steps to use the newly created theme on your pages.
Using the CSS output
Just copy the CSS output to a .css file and include it in your page.
Using the LESS output
The LESS output of the ThemeBuilder depends on the template.less theme template that is distributed along with the Kendo UI source. Save the LESS output to a .less file alongside the template.less and refer to the official LESS documentation on the various ways you can process it.
The common CSS files (kendo.common.css when using Kendo UI Web or kendo.dataviz.css when using Kendo UI DataViz) should always be registered on the page, even when using ThemeBuilder-generated themes.