<body>
<nav class="navbar navbar-default navbar-inverse" role="navigation">
  <div class="container-fluid">
    <!-- Brand and toggle get grouped for better mobile display -->
    <div class="navbar-header">
      <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1">
        <span class="sr-only">Toggle navigation</span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
      </button>
      <a class="navbar-brand" href="#">Login dropdown</a>
    </div>

    <!-- Collect the nav links, forms, and other content for toggling -->
    <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
      <ul class="nav navbar-nav">
        <li class="active"><a href="#">Link</a></li>
        <li><a href="#">Link</a></li>
        <li class="dropdown">
          <a href="#" class="dropdown-toggle" data-toggle="dropdown">Dropdown <span class="caret"></span></a>
          <ul class="dropdown-menu" role="menu">
            <li><a href="#">Action</a></li>
            <li><a href="#">Another action</a></li>
            <li><a href="#">Something else here</a></li>
            <li class="divider"></li>
            <li><a href="#">Separated link</a></li>
            <li class="divider"></li>
            <li><a href="#">One more separated link</a></li>
          </ul>
        </li>
      </ul>
      <form class="navbar-form navbar-left" role="search">
        <div class="form-group">
          <input type="text" class="form-control" placeholder="Search">
        </div>
        <button type="submit" class="btn btn-default">Submit</button>
      </form>
      <ul class="nav navbar-nav navbar-right">
        <li><p class="navbar-text">Already have an account?</p></li>
        <li class="dropdown">
          <a href="#" class="dropdown-toggle" data-toggle="dropdown"><b>Login</b> <span class="caret"></span></a>
			<ul id="login-dp" class="dropdown-menu">
				<li>
					 <div class="row">
							<div class="col-md-12">
								Login via
								<div class="social-buttons">
									<a href="#" class="btn btn-fb"><i class="fa fa-facebook"></i> Facebook</a>
									<a href="#" class="btn btn-tw"><i class="fa fa-twitter"></i> Twitter</a>
								</div>
                                or
								 <form class="form" role="form" method="post" action="login" accept-charset="UTF-8" id="login-nav">
										<div class="form-group">
											 <label class="sr-only" for="exampleInputEmail2">Email address</label>
											 <input type="email" class="form-control" id="exampleInputEmail2" placeholder="Email address" required>
										</div>
										<div class="form-group">
											 <label class="sr-only" for="exampleInputPassword2">Password</label>
											 <input type="password" class="form-control" id="exampleInputPassword2" placeholder="Password" required>
                                             <div class="help-block text-right"><a href="">Forget the password ?</a></div>
										</div>
										<div class="form-group">
											 <button type="submit" class="btn btn-primary btn-block">Sign in</button>
										</div>
										<div class="checkbox">
											 <label>
											 <input type="checkbox"> keep me logged-in
											 </label>
										</div>
								 </form>
							</div>
							<div class="bottom text-center">
								New here ? <a href="#"><b>Join Us</b></a>
							</div>
					 </div>
				</li>
			</ul>
        </li>
      </ul>
    </div><!-- /.navbar-collapse -->
  </div><!-- /.container-fluid -->
</nav>
</body>
body{
    background:url('http://www.wallpaperup.com/uploads/wallpapers/2012/10/21/20181/cad2441dd3252cf53f12154412286ba0.jpg');
    padding:50px;
}

#login-dp{
    min-width: 250px;
    padding: 14px 14px 0;
    overflow:hidden;
    background-color:rgba(255,255,255,.8);
}
#login-dp .help-block{
    font-size:12px    
}
#login-dp .bottom{
    background-color:rgba(255,255,255,.8);
    border-top:1px solid #ddd;
    clear:both;
    padding:14px;
}
#login-dp .social-buttons{
    margin:12px 0    
}
#login-dp .social-buttons a{
    width: 49%;
}
#login-dp .form-group {
    margin-bottom: 10px;
}
.btn-fb{
    color: #fff;
    background-color:#3b5998;
}
.btn-fb:hover{
    color: #fff;
    background-color:#496ebc 
}
.btn-tw{
    color: #fff;
    background-color:#55acee;
}
.btn-tw:hover{
    color: #fff;
    background-color:#59b5fa;
}
@media(max-width:768px){
    #login-dp{
        background-color: inherit;
        color: #fff;
    }
    #login-dp .bottom{
        background-color: inherit;
        border-top:0 none;
    }
}

External CSS

  1. https://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/css/bootstrap.min.css
  2. //maxcdn.bootstrapcdn.com/font-awesome/4.2.0/css/font-awesome.min.css

External JavaScript

  1. //cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js
  2. https://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/js/bootstrap.min.js