How to 'hide' :first-line for white-space:pre-line in FIREFOX browser
<p>When I use</p>

<pre><code>white-space: pre-line;
word-break: break-word;
</code></pre>

<p>...there is one additionl line before text. To hide it, I used: </p>

<pre><code>.class:first-line { line-height: 0; }
</code></pre>

<p>...and it is working in Chrome browser, but not in the Firefox.</p>

<p>Here is a working fiddle and please <strong>open it in Firefox</strong> : <a href="https://jsfiddle.net/t3qj51co/2/" rel="noreferrer">https://jsfiddle.net/t3qj51co/2/</a></p>

<p><a href="https://i.stack.imgur.com/Q7k2G.png" rel="noreferrer"><img src="https://i.stack.imgur.com/Q7k2G.png" alt="enter image description here"></a></p>