Resize or move a div when clicking on a button

[Keisha]

Hello,

I want to have the height of the "header" in dark gray smaller.
And when I click on the Main Navigation button in red it will resize or move down to display the menu.

Right now the issue is that the eight of the header in gray is to big.

http://bruyere.org/en/meeting-the-ne...-our-community

Thanks

[VIPStephan]

Your link is screwed up.