What should a responsive website look like?

Question

HTML

There is a site layout for example and 3 of its versions, for a resolution of 1200px, for a resolution of 768px and for a resolution of 320px.

A bit confused,
what should the site look like at 321px? Like on 320 or like on 768?
Which one at 767px and which one at 769px?
And what about 1999px and 12001?

Answer 1

Look, if you have layouts for resolutions 1200px, 768px and 320px, unless otherwise agreed with the designer or client, usually means:
from ∞ to 1201px - you layout the layout as in the layout with 1200px (container fix 1200 in pixels)
from 1200px to 769px - you typeset as in the 768px layout (fixed container 768 in pixels)
from 768 to 320px - layout with 320px (floating container in%)
Everything below 320px makes no sense to typeset, no one has been sitting with this resolution for a long time. These are very old smartphones.
For the most part, you need to discuss such issues with the designer, because designs are different and it is not always possible to make pixel-to-perfect (especially a lot of hassle with adaptive) and most often you can allow some conventions