You can place the 2 containers on top of each other and fade in/out the top one - DEMO
HTML
<section>
<div id="lower">
<button> Close </button>
</div>
<div id="upper">
<button> Sign up </button>
</div>
</section>
CSS
div {
position: absolute;
left: 20px;
top: 20px;
height: 300px;
width: 400px;
line-height: 300px;
text-align: center;
}
#lower { background: honeydew; }
#upper { background: beige; }
jQuery
$("#upper button").on("click", function() {
$("#upper").fadeOut(300);
});
$("#lower button").on("click", function() {
$("#upper").fadeIn(300);
});