title: how to detect if viewport unit is supported by browser?
body: <p>I'm planning to make very responsive website. For this, I'm including external stylesheet currently.</p>
  
  <p>But I want to include it for only those browsers which supports viewport units such as vw. </p>
  
  <p>So, how could I detect for browser that it supports or not.</p>
  
  <p>Please note: I don't want to include modernizer.</p>