i have dropdown menu from bootstrap 4.In adaptive small screen, I have hamburger, there has title dropdown its opens another one dropdown.So, when I open title dropdown to see what inside, dropdown automatically close full dropdown. Here`s code
<nav class="navbar navbar-expand-lg navbar-header">
<div class="container">
<div class="navbar-translate">
<a class="navbar-brand" href="./" rel="tooltip" title="Казахстанский инженерно-технологический университет" data-placement="bottom">
<img src="assets/img/logo_new.png" width="180">
</a>
<button class="navbar-toggler navbar-toggler" type="button" data-toggle="collapse" data-target="#navigation" aria-controls="navigation-index" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-bar bar1"></span>
<span class="navbar-toggler-bar bar2"></span>
<span class="navbar-toggler-bar bar3"></span>
</button>
</div>
<div class="collapse navbar-collapse" style="background-color: white;" id="navigation">
<ul class="navbar-nav mr-auto" id="testing">
<div class="nav-item dropdown">
<a class="nav-link dropdown-toggle myclass" data-toggle="dropdown" href="#" id="dropdownMenuButton" role="button" aria-haspopup="true" aria-expanded="false"><?=$m_admission[$_SESSION['lang']]?></a>
<ul class="dropdown-menu">
<a class="dropdown-item" href="?page=undergraduate"> <?=$b_undergraduate[$_SESSION['lang']]?> </a>
<a class="dropdown-item" href="?page=graduate"> <?=$b_graduate[$_SESSION['lang']]?> </a>
<a class="dropdown-item" href="https://kazetu.edu.kz/sites/dl/" target="_blank"> <?=$b_distance_learning[$_SESSION['lang']]?> </a>
<a class="dropdown-item" href="https://college.kazetu.edu.kz/"> <?=$b_college[$_SESSION['lang']]?> </a>
<a class="dropdown-item" href="https://zerde.kazetu.kz/?lang=ru" target="_blank"> <?=$zerde_kazetu_reg[$_SESSION['lang']]?> </a>
</ul>
</div>
</ul>
</div>
</div>
</nav>
</header>
