Part of Jekyll template ending up in the style.css file

I am using the Jeykll stater and noticed that whilst I have serving my project part of my template was ending up in _site/css/style.css. Any idea why this may be happening?

style.css

<head>
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta charset="utf-8">
  <link rel="stylesheet" href="/css/site.css">
  <link rel="icon" href="/assets/favicon.ico">
</head>
<html>
  <body class="w-full h-full p-0 m-0">
    <div class="flex w-full h-full">
      <aside class="flex-none w-1/6 h-full px-8 py-10 overflow-y-auto shadow-md">
        <div class="border-bottom">
          <span class="-mb-3 text-gray-50 h6">Project</span>
          <h1 class="mb-10 display-3">Atom</h1>
        </div>

        <nav class="">
          <ul>
            <li class="mb-1 hover:bg-violet-10">
              <a href="/">Home</a>
            </li>
            <li class="mb-1 hover:bg-violet-10">
              <a href="/spacing-and-sizing">Spacing & Sizing</a>
            </li>
            <li class="mb-1 hover:bg-violet-10">
              <a href="/typography">Typography</a>
            </li>
          </ul>
        </nav>

      </aside>
      <section class="flex-grow h-full py-10 overflow-y-auto">
        @import url('https://fonts.googleapis.com/css?family=Roboto+Slab|Roboto:300,300i,400,400i,500,500i,700,700i&display=swap');

@import url("https://use.typekit.net/ltq4kgq.css");

/* Front matter is necessary for Jekyll */

/*! normalize.css v8.0.1 | MIT License | github.com/necolas/normalize.css */

/* Document
   ========================================================================== */

/**
 * 1. Correct the line height in all browsers.
 * 2. Prevent adjustments of font size after orientation changes in iOS.
 */

html {
  line-height: 1.15; /* 1 */
  -webkit-text-size-adjust: 100%; /* 2 */
}

tailwindlabs / tailwindcss-setup-examples

Part of Jekyll template ending up in the style.css file #59