title: Bootstrap4 Disabled button white instead of supposed color
body: <p>I am using a bootstrap button on one of my page, that is disabled, and the styling seems to not be working properly </p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
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  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.0.0-alpha.6/css/bootstrap.min.css"&gt;
  &lt;button disabled class="btn btn-primary"&gt;suivant&lt;/button&gt;
  &lt;button class="btn btn-primary disabled"&gt;suivant&lt;/button&gt;</code></pre>
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  </div>
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  <p>I tried these 2 ways and the result look like this for both approach: <a href="https://i.stack.imgur.com/5Y98g.png" rel="nofollow noreferrer">initial look</a> || <a href="https://i.stack.imgur.com/ccKnP.png" rel="nofollow noreferrer">on Mouse over</a></p>
  
  <p>EDIT: Important to mention that i only have bootstrap4, no personnal style sheet and no other themes</p>
  
  <p>This is a react Project, className is used instead of class</p>