Twenty Fifteen responsive menu not work

Hi everyone. I’m quite new in wordpress theme. I’m just trying to modify a simple twenty fifteen theme. I’ll udnerstand how to do that, but now the nav-button menu is not still worrking when it starts to be “responsive”. here the link of my wordpress. You could test by yourself just reducing the dimension of the page. If you click on the button menu, hes not showing nothing. The “search” and “tagcloud” that you can see on the left-bar are inside “widget area”.

https://www.mm85.eu/gneorg/news/