What is best property value for width, height and font-size etc. to make webpage responsive.

Answer 1

I imagine there are thousands of different layouts and configurations which are responsive and look decent. No single magic value.
You should do some research to find guidelines how responsive pages are structured and styled (it's not just about the css but also the html layout).

https://kinsta.com/blog/responsive-web-design/

And many more sites online deal with nitty gritty details.

Answer 2

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