Mobile responsiveness for the layout. A suggested approach and demonstrated result.

I see already there are pending issues and a PR #650 on the topic. I solved this in my translation. Here is the commit: https://github.com/mmcgrana/gobyexample/commit/434e655779c5ad4505a09bbe5c885e8112aaec0a And here are some results: https://слово.бг/го-в-примери/index.html https://слово.бг/го-в-примери/if-else.html

You can check this right in the browser by opening DevTools and see different mobile views. You can see it right now on your mobile phone too. How about such approach?