responsive site on mobile

Hi I have a site taken from you, precisely Computers Version 2.4.4

At the top of the site where I put a page on desktop mode you can see but in mobile mode no, how can I solve this problem? Thank you

desktop mode

[url=https://ibb.co/dNpVE7][img]https://preview.ibb.co/mpMMMn/desktop.jpg[/img][/url]

mobile mode

[url=https://imgbb.com/][img]https://image.ibb.co/hSjQgn/mobile.jpg[/img][/url]