What is the best way to change the design of the site?

Question

1C-Bitrix

Task: change the design of the site.
Problem: Orders are constantly being placed on the site. In general, there is active activity.
Question: How to change the design so as not to interfere with the site? You can deploy a backup copy at home, but then it turns out you will have to do a file transfer.
Professionals, please advise how best to organize this.

Answer 1

What design do you want to change? Whole site?
In any case, you need to deploy a copy of the site to test the new design. And after that, the transfer will not be difficult: you just need to transfer the directory with the new site template to the working site and activate the template in the admin panel. But keep in mind: this will only work if the previous template was developed correctly, without crutches.
If your new design also changes the structure of the pages (not only the appearance), you will also have to transfer the page files. There is no escape from this.