title: How does line-height vertically center text?
body: <p>I'm trying to understand why the <code>line-height</code> CSS property places the text vertically in the middle of this button:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>.btn-order {
      width: 220px;
      height: 58px;
      font-size: 24px;
      padding: 0;
      text-align: center;
      vertical-align: middle;
      line-height: 58px;
      border: 1px solid black;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="btn-order"&gt;Complete Order&lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>