JSFiddle - React, Tailwind, and code Playground

HTML

<dl class="code">
    <dt data-line-number="1"></dt>
    <dd>public static function autoload($className)</dd>
    <dt data-line-number="2"></dt>
    <dd>{</dd>
</dl>

CSS

.code dt:before {
   content: attr(data-line-number);
}
dt {width: 10px; float: left;}