What width should the site be? And on what?

Question

css

The site will have several different sections, such as a personal account and a store. The seller's personal account will be full screen (100%), and there will be statistics, reporting, etc.
The store itself is another matter. Given the specifics of the product, the content block should be as wide as possible. Here's how much it's possible. But there will also be two sidebars on the site. To the left and right of the content block. We do not take into account mobile layout, there will be a different principle of interaction.
Looking at the statistics on monitors, I understand that disregarding monitors less than 1280 is not an option. There are still a lot of them. But I would like to make only the central part more than 800 pixels. And with this size of the center sidebars simply do not fit.
As I understand it, the standard is now 1440 for "wide" sites (a toaster, for example). Accordingly, I will proceed from this permission. But the question remains of how to do this for narrower monitors. You won't be able to "squeeze" the sidebars. There will be rigid element sizes. It remains to shrink the content in the center? For monitors less than 1280 I think antics is not an option, it will be very narrow. It remains to make some of the sidebars "folding" (there will be a menu on one, I think it can be pushed a little by removing the rest). Or maybe there are some better options, so as not to "infringe" on old monitors?
Also interested in the framework for adapting this all. Bootstrap, as I understand it, already considers everything that is more than 1200 "big" and does not understand further. Accordingly, you need something that can work with screens up to fullhd at least (a reserve for the future). Can you recommend anything? Preferably with good documentation and support and universal. Since the project is not for one year.

Answer 1

Use bootstrap grids, all sizes are there
https://bootstrap-4.ru/docs/4.1/layout/grid/#grid-...

Answer 2

Make the site a comprehensive width, if something does not fit, then shrink, restructure. Why two sidebars on a small screen? Shrink them down to a strip with icons, or remove them altogether. There are plenty of similar designs, google admin panel template.
Why is bootstrap not suitable? Sources are available, add as many breakpoints as you like, change the standard ones to whatever you like and go ahead. It's all in the configs.

Answer 3

Looking at the statistics on monitors, I understand that disregarding monitors less than 1280 is not an option. There are still a lot of them.

for a resolution of 1280x1024, only 6% of users is a lot?)))
go further:
half of the 6% are aunts in research institutes and design bureaus, who the hell knows why they climb into the Internet from their ancient 14-inch square monitors.
All other resolutions less than 1280 are tablets, etc.
Therefore, take 1200 and dance from it. As actually done in BS