title: Make a very thin white line in CSS
body: <p>This may sound quite silly, but I have no idea how to make a thin line smaller then 1px. </p>
  
  <p>What I am looking for is something like this:</p>
  
  <p><a href="https://www.simple.com/" rel="nofollow">https://www.simple.com/</a></p>
  
  <p>If you do:</p>
  
  <pre><code>    .nav-bar {
         border-bottom: 1px;
      }
  </code></pre>
  
  <p>It's almost twice, if not three times as thick. As you are also probably aware, doing <code>1em</code> would just round up to <code>1px</code>.</p>
  
  <p>Anyone have any ideas?</p>