How to choose the width when layout?

Question

css

Hello, recently I began to actively make up pages, "to fill my hand", but now I don’t understand 1 moment. For example, I have a psd landing page 1200 pixels wide. Some blocks go full width, some I make 1200 and align the content in the center, and so on. It comes out pretty and looks like something real. For example, here is the last one https://newalastor.github.io
And what if the layout width is set to 1600 by default? Do I need to set the same block width? That's a lot enough. How do you go about these measurements?
Thank you for your attention.

Answer 1

It is necessary to make up the way the designer intended (ideally - pixel perfect). Everything has already been thought of for you, do it according to plan.