JSFiddle - React, Tailwind, and code Playground

HTML

<pre>
Line 1
Line 2 <span class=remark>Remark 1</span>
Line 3
Line 4 <span class=remark>Remark 2</span>
Line 5
</pre>

CSS

pre {
  border: 1px solid #000;
  padding: 5px;
}

.remark {
  border: 1px solid #f00;
  float: right;
}