Live Demo: Bootstrap Navbar with Inline Login Form in Dropdown

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<title>Bootstrap Navbar with Inline Login Form in Dropdown</title>
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Open+Sans:400,600">
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/css/bootstrap.min.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<script src="https://code.jquery.com/jquery-3.5.1.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/popper.js@1.16.0/dist/umd/popper.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/js/bootstrap.min.js"></script>
<style>
body {
	font-family: 'Open Sans', sans-serif;
}
.form-control {
	box-shadow: none;
	border-radius: 4px;        
	border-color: #dfe3e8;
}
.navbar {
	background: #fff;
	padding-left: 16px;
	padding-right: 16px;
	border-bottom: 1px solid #dfe3e8;
	border-radius: 0;
}
.navbar .navbar-brand {
	font-size: 20px;
	padding-left: 0;
	padding-right: 50px;
}
.navbar .navbar-brand b {
	color: #29c68c;		
}
.navbar a, .navbar a:active {
	color: #999;
	background: transparent;
}
.navbar .navbar-nav a:hover, .navbar .navbar-nav a:focus {
	color: #29c68c !important;
}
.navbar .navbar-nav > a.active, .navbar .navbar-nav.show > a {
	color: #26bb84 !important;
	background: transparent !important;
}
.navbar .form-inline .input-group-text {
	box-shadow: none;
	border-radius: 2px 0 0 2px;
	background: #f5f5f5;
	border-color: #dfe3e8;
	font-size: 16px;
}
.navbar .form-inline i {
	font-size: 16px;
}
.navbar .form-inline .btn {
	border-radius: 2px;
	color: #fff;
	border-color: #29c68c;
	background: #29c68c;
	outline: none;
}
.navbar .form-inline .btn:hover, .navbar .form-inline .btn:focus {
	border-color: #26bb84;
	background: #26bb84;
}
.navbar .search-form {
	display: inline-block;
}
.navbar .search-form .btn {
	margin-left: 4px;
}
.navbar .search-form .form-control {
	border-radius: 2px;
}
.navbar .login-form .input-group {
	margin-right: 4px;
	float: left;
}
.navbar .login-form .form-control {
	max-width: 158px;
	border-radius: 0 2px 2px 0;
}    	
.navbar .navbar-right .dropdown-toggle::after {
	display: none;
}
.navbar .dropdown-menu {
	font-size: 14px;
	border-radius: 1px;
	border-color: #e5e5e5;
	box-shadow: 0 2px 8px rgba(0,0,0,.05);
}
.navbar .dropdown-menu a {
	padding: 6px 20px;
}
.navbar .login-dropdown .dropdown-menu {
	width: 505px;
	padding: 20px;
	left: auto;
	right: 0;        
}
.navbar .login-dropdown .dropdown-toggle::after {
	display: none;
}
@media (min-width: 1200px){
	.search-form .input-group {
		width: 300px;
		margin-left: 30px;
	}
}
@media (max-width: 768px){
	.navbar .dropdown-menu {
		width: 100%;
		background: transparent;
		padding: 10px 20px;
	}
	.navbar .input-group {
		width: 100%;
		margin-bottom: 15px;
	}
	.navbar .input-group .form-control {
		max-width: none;			
	}
	.navbar .login-form .btn {
		width: 100%;
	}
}
</style>
</head> 
<body>
<nav class="navbar navbar-expand-lg navbar-light bg-light">
	<a href="#" class="navbar-brand">Brand<b>Name</b></a>  		
	<button type="button" class="navbar-toggler" data-toggle="collapse" data-target="#navbarCollapse">
		<span class="navbar-toggler-icon"></span>
	</button>
	
	<div id="navbarCollapse" class="collapse navbar-collapse justify-content-start">
		<div class="navbar-nav">
			<a href="#" class="nav-item nav-link">Home</a>
			<a href="#" class="nav-item nav-link">About</a>			
			<div class="nav-item dropdown">
				<a href="#" data-toggle="dropdown" class="nav-item nav-link dropdown-toggle">Services</a>
				<div class="dropdown-menu">					
					<a href="#" class="dropdown-item">Web Design</a>
					<a href="#" class="dropdown-item">Web Development</a>
					<a href="#" class="dropdown-item">Graphic Design</a>
					<a href="#" class="dropdown-item">Digital Marketing</a>
				</div>
            </div>
			<a href="#" class="nav-item nav-link active">Pricing</a>
			<a href="#" class="nav-item nav-link">Blog</a>
			<a href="#" class="nav-item nav-link">Contact</a>
        </div>
		<form class="navbar-form form-inline search-form">
			<div class="input-group">
				<input type="text" class="form-control" placeholder="Search...">
				<span class="input-group-btn">
					<button type="button" class="btn btn-default"><i class="fa fa-search"></i></button>
				</span>
			</div>
		</form>
		<div class="navbar-nav ml-auto">
			<div class="nav-item dropdown login-dropdown">
				<a href="#" data-toggle="dropdown" class="nav-item nav-link dropdown-toggle"><i class="fa fa-user-o"></i> Login</a>
				<div class="dropdown-menu">					
                    <form class="form-inline login-form" action="/examples/actions/confirmation.php" method="post">
                        <div class="input-group">
							<div class="input-group-prepend">
								<span class="input-group-text">
									<span class="fa fa-user"></span>
								</span>                    
							</div>
                            <input type="text" class="form-control" placeholder="Username" required>
                        </div>
                        <div class="input-group">
							<div class="input-group-prepend">
								<span class="input-group-text">
									<i class="fa fa-lock"></i>
								</span>                    
							</div>
                            <input type="text" class="form-control" placeholder="Password" required>
                        </div>
                        <button type="submit" class="btn btn-primary">Login</button>
                    </form>
                </div>
            </div>			
        </div>
	</div>
</nav>
</body>
</html>