If the used framework is based on a global CSS classes it is expected to have problems, not only with our products, but with each web based component, as the global CSS is applied to the HTML elements but not to specific ID or CSS classes and that breaks the layout of the component.
In short, in the case of bootstrap, it uses a lot of global styles applied to almost each single HTML element. For example it could give the SPAN element border: 2px solid red. As our controls are web based, they are built with HTML and we use a lot of SPAN elements in the rendering. If we did not explicitly specified that some specific class should not be bordered, then it will be bordered by the boolstrap styles and it will break the control.
The framework that we have a good experience with are: MS AjaxToolKit, jQueriUI
All the best,
the Telerik team
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