Mobile header adjustment

I need a developer who is familiar with Wordpress, WPbakery and Slider Revolution 6.

My website, www.wefindcarsforyou.co.uk was built using all of the above plugins, but I cant work out what was used to do the Header of the website and I would like to change the way it is displayed on mobile phones.
Currently on mobile devices the header is on a white background, but I would like the logo to be displayed as on the desktop and the menu options to appear as a burger menu.

I would like the website displayed the same as the desktop on tablets, ipads, notebooks.
I only want it to change for any mobile phone device.

I would like to be shown how to edit the header as well for future reference.

Please respond with fixed price quotes for what you think this job would require.

Many thanks

Matt