First I want to note that for our preview functionality we use custom logic, not the standard ASP.NET rendering engine. Therefore, you see that your code is correctly rendered, however due to the different browsers logic it is possible that there are differences in what the user actually sees in the browsers.
Can you elaborate a bit more on what do you mean by " every other environment " and also provide us with some sample code that we can test your scenario locally and investigate further.
the Telerik team
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