Navigation bar / menu in header problem – when narrowing window it moves lower

Dear Sirs!

I have unfortunatelly following problem with your HIGH END theme.

When I narrow the browser window, first the menu items move closer to the logo but when reaching the place of logo, the whole menu is shifted down over text or image whatever content is below.

Based on content it can also become unreadably but in anyway it messes up the page look.

I have however noticed that if I narrow the browser window further eventually when it comes almost to the end it turn to the icon of mobile menu.

How can I set it that it Will sooner turn into mobile menu icon.

Please help.

Kind regards