What are the minimum sizes to use for adaptive layout?

Question

Adaptive design

I heard that the minimum screen width is considered to be 320px, supposedly this is the width of the iphone 4
And I always did this, in chrome, when you select the iphone 5 (there is no four), everything looks gorgeous.
But, then somehow I had an iphone 5s in my hands and I decided to look at how the newly created site would look like in it and imagine my surprise that the site turned out to be with a broken layout. By eye, I determined that the width there is about 250px, when compared with a browser on a computer, when you compress to such a width.

Answer 1

Of course, you can do it under 140px, the right, as the author of the layout, is up to you, but I would do this:
1. I went to the site: https://en.screenresolution.org/
2. I would look at the most common screen resolution
3. I looked would be the minimum common (which is used by 1%+ users)
4. And would make a layout with an emphasis on them.

Answer 2

I always adapt the logos and header to 280px.