Hi Anne,

The RadCheckBox and RadCheckBoxList components offer only Lightweight rendering, since the classic one was discontinued as of R3 2015 and not available during their planning and development.

That's why if the RenderMode property of RadButton is not set to Lightweight, it defaults to Classic render mode due to backwards compatibility reasons, there is mixture of classic and lightweight render modes on the page, which cause the problem as explained in this troubleshooting article: Incorrect or Distorted Appearance.

To avoid the mixture of render modes, we recommend all Telerik components on the page to have set RenderMode="Lightweight".


Best regards,
Rumen
Progress Telerik