title: What are the disadvantages of vh and vw units?
body: <p>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?</p>
  <p>Thank you very much!</p>