Can you show how the code is entered?

can you show how the code is entered? your css windows are blank. Is it just raw css like

text-align:center;

or are their special characters?

Are you going to add custom CSS code to the widget or to the form? 

I think the text-align: center; is incomplete. 

Please provide the form URL so we can assist you properly. Also, let us know what you're trying to achieve so we can provide you with the custom CSS code.

https://www.jotform.com/help/117-How-to-Inject-Custom-CSS-Codes

https://www.jotform.com/help/428-How-to-Inject-CSS-Codes-to-Widgets

We'll wait for your reply.