Here is the head in master page where i added the link:
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<!-- this is the link -->
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" integrity="sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" crossorigin="anonymous">
<meta content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no" name="viewport">
<link rel="stylesheet" href="{{ asset('vendor/adminlte/vendor/bootstrap/dist/css/bootstrap.min.css') }}">
<link rel="stylesheet" href="{{ asset('vendor/adminlte/vendor/font-awesome/css/font-awesome.min.css') }}">
<link rel="stylesheet" href="{{ asset('vendor/adminlte/vendor/Ionicons/css/ionicons.min.css') }}">
@if(config('adminlte.plugins.select2'))
<link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/select2/4.0.3/css/select2.css">
@endif
<link rel="stylesheet" href="{{ asset('vendor/adminlte/dist/css/AdminLTE.min.css') }}">
@if(config('adminlte.plugins.datatables'))
<link rel="stylesheet" href="//cdn.datatables.net/v/bs/dt-1.10.18/datatables.min.css">
@endif
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Source+Sans+Pro:300,400,600,700,300italic,400italic,600italic">
And here is the header and NavBar in other page , note that i have extended master page. I couldn't bring all the codes properly.
<header class="main-header">
@if(config('adminlte.layout') == 'top-nav')
<nav class="navbar navbar-static-top">
<div class="container">
<div class="navbar-header">
<a href="{{ url(config('adminlte.dashboard_url', 'home')) }}" class="navbar-brand">
{!! config('adminlte.logo', '<b>Admin</b>LTE') !!}
</a>
<button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar-collapse">
<i class="fa fa-bars"></i>
</button>
</div>
<div class="collapse navbar-collapse pull-left" id="navbar-collapse">
<ul class="nav navbar-nav">
@each('adminlte::partials.menu-item-top-nav', $adminlte->menu(), 'item')
</ul>
</div>
@else
<div class="pull-left">
<a href="{{ url(config('adminlte.dashboard_url', 'home')) }}" class="logo" style="font-family: IRANSans;color: white; background-color: #109e7a">
<span class="logo-mini">{!! config('adminlte.logo_mini', '<b>A</b>LT') !!}</span>
<!-- logo for regular state and mobile devices -->
<span class="logo-lg">{!! config('adminlte.logo', '<b>Admin</b>LTE') !!}</span>
</a>
</div>
<!-- Header Navbar -->
<nav class="navbar navbar-static-top" role="navigation">
<!-- Sidebar toggle button-->
<a href="#" class="sidebar-toggle" data-toggle="push-menu" role="button">
<span class="sr-only">{{ trans('adminlte::adminlte.toggle_navigation') }}</span>
</a>
@endif
<!-- Navbar Right Menu -->
<div class="navbar-custom-menu">
<ul class="nav navbar-nav">
<li style="font-family: IRANSans">
@if(config('adminlte.logout_method') == 'GET' || !config('adminlte.logout_method') && version_compare(\Illuminate\Foundation\Application::VERSION, '5.3.0', '<'))
<a href="{{ url(config('adminlte.logout_url', 'auth/logout')) }}">
<i class="fa fa-fw fa-power-off"></i> Exit
</a>
@else
<a href="#"
onclick="event.preventDefault(); document.getElementById('logout-form').submit();">
Exit <i class="fa fa-fw fa-power-off"></i>
</a>
<form id="logout-form" action="{{ url(config('adminlte.logout_url', 'auth/logout')) }}" method="POST" style="display: none;">
@if(config('adminlte.logout_method'))
{{ method_field(config('adminlte.logout_method')) }}
@endif
{{ csrf_field() }}
</form>
@endif
</li>
</ul>
</div>
</nav>
@if(config('adminlte.layout') == 'top-nav')
</div>
@endif
</nav>
</header>
When i added this link, navbar Exit Button disappears and the height of header increases.. I'm new to html and css. Thank you for helping!