Website looks bad on mobile device

My website looks like I want on the laptop.
https://www.heravanwillick.nl
But on a mobile device it doesn’t show my blog on the home page, it just says ‘front page’.
Also the menus are all in the left top corner, while i want them similar to the laptop version in the header.
Please, can someone tell me how to fix this??
It’s the selfhosted version of Oxygen theme.