Looking for responsive code to make header opt-in perform correctly.

Hello, I have added an opt-in form to the header area on the following site: http://www.clearcreativecoaching.com/ In order to get the opt-in form to show up in the header area correctly, I had to add the header image as a background image and installed the Openhook plugin to give me a header hook to place the opt-in code.

Here’s my issue…. When I minimize my browser window, the opt-in form moves out of place. Is there an @media code that I can place in the Custom CSS area that will target the opt-in form in order to make it more responsive instead of fixed so that it will remain in the correct place? Any help you can give will be appreciated. Thanks.