I am pretty new to front-end development. I wonder what are the disadvantages of vh and vw? I have been always using them because they can adjust the font size based on the screen size. However, I didn't see many people use them as much as I do and saw online that most people prefer to use em. So, it is okay to keep always using vh and vw? What are their disadvantages?
Thank you very much!
The disadvantage is the same as the advantage: it is relative to the screen dimensions.
This is something you probably don't want for a font, since "absolute" units like px and cm already are relative to the perceived size*, which accounts for how distant the observer is from the screen. For example: If a user is using a mobile phone to navigate a web page, you would want the font size to remain constant whether it has a big screen or a small screen.
So I would recommend using an absolute unit like px to set the font size, border thicknesses, etc...
* According to the spec. In practice, the size of px is often synchronized with the OS settings.
