Position an element directly next to stackable menu



I’m just starting with Semantic UI and would like to create a theme similar to “Jumbotron” at Semantic UI Forest.

The major difference is that I want the navigtaion menu to be responsive so I added the stackable class. The menu itself gets stacked when I change the screen size but it hides the “jumbotron”. I want the jumbotron positioned directly next to the navigation bar in either mode, stacked or unstacked.

Please check out the example on codepen.io and this screenshot. The red area shall always be aligned below the menu.

What am I missing here?