When I look at my site[1] e.g. from a chrome browser it looks like it's supposed to be (second image).

When I see it on a mobile device and on testing tools like [2] all the code formatting is gone (first image)

Please advise.

[1] https://reliableembeddedsystems.com/res-build-framework-qemux86-64-virt-master-nanbield/
[2] https://responsivetesttool.com/