<div class="navbar" id="myTopnav">
<a href="#home">Inicio</a>
<a href="#news">Noticias</a>
<div class="dropdown">
<button class="dropbtn">Iniciar sesión
<i class="fa fa-caret-down"></i>
</button>
<div class="dropdown-content">
<form method="post" action="/login.phtml">
<input type="hidden" id="templateLoginDest" name="destination" value="%2F">
<table style="width: 350px;" align="center">
<tbody><tr>
<td valign="top" width="100px"><b>Usuario:</b></td>
<td valign="top"><input type="text" name="username" id="templateLoginPopupUsername" size="30"></td>
</tr>
<tr>
<td valign="top"><b>Contraseña:</b></td>
<td valign="top"><input type="password" name="password" size="30"><br><a href="/account/passwordreset.phtml" style="font-size: 8pt;">Recordar contraseña</a><br><br></td>
</tr>
<tr>
<td colspan="2" align="center"><input type="submit" value="Entrar!"></td>
</tr>
</tbody></table>
</form>
</div>
<a href="javascript:void(0);" class="icon" onclick="myFunction()">&#9776;</a>
</div> 
</div>
<script>function myFunction() {
    var x = document.getElementById("myTopnav");
    if (x.className === "navbar") {
        x.className += " responsive";
    } else {
        x.className = "navbar";
    }
}
</script>

.navbar {
overflow: hidden;
background-color: #333;
font-family: Arial;   
}
.navbar a {
float: left;
font-size: 16px;
color: white;
text-align: center;
padding: 14px 16px;
text-decoration: none;
}
.dropdown {
float: left;
overflow: hidden;
}
.dropdown .dropbtn {
font-size: 16px; 
border: none;
outline: none;
color: white;
padding: 14px 16px;
background-color: inherit;
}
.navbar a:hover, .dropdown:hover .dropbtn {
background-color: red;
}
.dropdown-content {
display: none;
position: fixed;
background-color: black;
width: 350px;
height: auto;
color: #fff;
float: left;
}
.dropdown-content a {
float: none;
color: #fff;
padding: 12px 16px;
text-decoration: none;
display: block;
text-align: left;
}
.dropdown-content a:hover {
  background-color: #ddd;
}
.dropdown:hover .dropdown-content {
display: block;
}
.navbar .icon {
display: none;
}
@media screen and (max-width: 600px) {
.navbar a:not(:first-child) {display: none;}
.navbar a.icon {
float: right;
display: block;
}
.navbar.responsive {position: relative;}
.navbar.responsive a.icon {
position: absolute;
right: 0;
top: 0;
}
    .article.responsive {
position: relative;
}
}
.navbar.responsive a {
float: none;
display: block;
text-align: left;
}