How to properly use css so that a web code will look the same on phone and on computer?

Answer 1

1. For functional webpage, they shouldn't look the same, for example, navigator should be a bar or a drop down menu depends on the mobile screen width

For example

https://code.sololearn.com/Wg22IhsSh93V/?ref=app

2. Use media query to detect screen orientation and screen width

Resources links to be provided upon request.

3. Use viewport units vw vh

4. Scale down the page when screen size is small.

Answer 2

You need to learn responsive web development.