title: Bootstrap navbar menu not displayed on mobile
body: <p>I am using bootstrap 4 to make a simple theme.
  My problem is, that when I view the page on mobile, and click the menu button, the menu shows up for 1 second, and then hide it self. If I click the button gain, it wont show up.</p>
  <p><a href="https://kozetgyapot-arak.hu/adatkezelesi-tajekoztato" rel="nofollow noreferrer">Demo site here</a></p>
  <p>My menu source code from the browser (I don't use the sticky classes)</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-html lang-html prettyprint-override"><code>&lt;header class="header header-sticky- header-transparent__"&gt;
    &lt;div class="container"&gt;
      &lt;div class="row"&gt;
        &lt;div class="col-12"&gt;
          &lt;nav class="navbar navbar-expand-lg"&gt;
            &lt;!-- Logo START --&gt;
            &lt;a class="navbar-brand" title="IQ Logistics Kft." href="https://kozetgyapot-arak.hu"&gt;
              &lt;img class="img-fluid" src="https://themes.potenzaglobalsolutions.com/html/bulky/images/logo.svg" alt="IQ Logistics Kft."&gt;
            &lt;/a&gt;
            &lt;button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation"&gt;
              &lt;span class="navbar-toggler-icon"&gt;&lt;/span&gt;
            &lt;/button&gt;
            &lt;div class="collapse navbar-collapse" id="navbarSupportedContent"&gt;
              &lt;ul class="navbar-nav m-auto_"&gt;
          &lt;li class="nav-item"&gt;&lt;a class="nav-link" title="Kezdőlap" href="https://kozetgyapot-arak.hu/"&gt;Kezdőlap&lt;/a&gt;&lt;/li&gt;&lt;li class="nav-item"&gt;&lt;a class="nav-link" title="Rólunk" href="https://kozetgyapot-arak.hu/rolunk"&gt;Rólunk&lt;/a&gt;&lt;/li&gt;&lt;li class="nav-item"&gt;&lt;a class="nav-link" title="Szolgáltatások" href="https://kozetgyapot-arak.hu/szolgaltatasok"&gt;Szolgáltatások&lt;/a&gt;&lt;/li&gt;&lt;li class="nav-item"&gt;&lt;a class="nav-link" title="Elérhetőségeink" href="https://kozetgyapot-arak.hu/elerhetosegeink"&gt;Elérhetőségeink&lt;/a&gt;&lt;/li&gt;            &lt;/ul&gt;
            &lt;/div&gt;
            &lt;div class="mr-5 mr-lg-0 d-sm-flex d-none align-items-center"&gt;
              &lt;a class="btn btn-primary" href="https://kozetgyapot-arak.hu/arajanlat-kerese"&gt;Árajánlat kérése &lt;i class="fa fa-chevron-right ml-1"&gt;&lt;/i&gt;&lt;/a&gt;
            &lt;/div&gt;
          &lt;/nav&gt;
        &lt;/div&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  &lt;/header&gt;</code></pre>
  </div>
  </div>
  </p>
  <p>Thank you, if someone can help me.</p>