Newsletter Subscription field in navigation bar.

Any advice pertaining to this matter is greatly appreciated. Currently on lacrosse-lounge.com you will notice I have a subscription form in the navigation bar. However when viewing the site in different widths the input field and submit button end up on different lines. I think it is important to have them both on the same line togather at any width the site is being displayed at. I also am noticing that when viewed on mobile devices overall the site isnt too apealing . Im open to all suggestions and thankful for any specific code that should be added or changed! Thanks again.