I hope your are talking about footer display..
Its just because your signout modal's div is not closed completely.. So Footer will appear when Signout modal appears..
Here is the DEMO
and here is what u need to change:
<div id="openModal2" class="modalDialog">
<div>
<a href="#close" title="Close" class="close">X</a>
<p>
Please fill out and click sign out.
</p>
<form action=".php" method="post" class="">
First Name:
<input type="text" name="fname"><br>
Last Name:
<input type="text" name="lname"><br>
<input type="submit" value="Sign Out">
</form>
</div>
</div>
Jus add one more div at the end as I have shown above...