title: how to write a css that only can be visible on desktop in bootstrap
body: <p>I rewrote a declaration</p>
  
  <pre><code> .navbar .nav {
      top:30px;
  } 
  </code></pre>
  
  <p>on the my css file, but I only want this declaration can be responded on desktop view, not in the phone veiw. How do I to write correctly? thank your help. </p>