Change color of a field when filled

I am sending long URLs that complete fields for clients when viewed.

How can I change the text style on the contents of a completed field?

change to bold, change color, change size, etc.

Unfortunately, it is not possible to change the property of a field when it is filled using JotForm builder. However, you may achieve this by downloading the full source code of the form and adding additional JavaScript code. When you get the source code to modify, you'll need to host the form on your webserver.

Please refer to the link below that might help you in achieving this requirement. 

http://stackoverflow.com/questions/17218987/changing-background-color-of-text-box-input-not-working-when-empty

An example with a textfield changing color when filled is shown below :

http://jsfiddle.net/2Xgfr/829/

Hope this information helps!