You can try adding the following CSS code in the head section of your page in order to ensure that the content in the cells of the table, generated by the RadSplitter, is aligned correctly.
Note that currently I am mostly guessing as to what your exact setup is and although I am willing to help you, I am unable to do so without a runnable project that matches your scenario. Please open a regular support ticket
and try modifying the attached sample so that the issue is reproducible. If this is not an option, you could also prepare and send a sample, runnable project that isolates the problem
so that we can inspect it locally and suggest a corresponding solution.
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed