CSS-only pre line numbers

HTML

<div class="container">
    <pre>
        hi wat
       r u doing
       ddfdf
       dfdfdfdfdf
       ff
       
    </pre>
</div>

CSS

body {
  background-color: #eee;
  color: #555;
}

pre {
  font-family: monospace;
  background-color: #fff;
  width: 27.5em;
  margin: 4em auto;
  padding: 0.5em;
  box-shadow: 0.1em 0.1em 0.5em rgba(0, 0, 0, 0.45);
  line-height: 0;
  counter-reset: line;
}
pre span {
  display: block;
  line-height: 1.2rem;
}
pre span:before {
  counter-increment: line;
  content: counter(line);
  display: inline-block;
  border-right: 1px solid #ddd;
  padding: 0 .5em;
  margin-right: .5em;
  color: #888888;
}