I have a document that includes a header (menu) and a footer in PHP:
<?php include('header.php'); ?>
<?php include('footer.php'); ?>
For some reason when opened on the browser it renders a gap between both without having any margins or CSS styles doing it:
This is part of the code generated, the gap appears between </header><footer>
:
<div class="ClearFloat"></div>
</nav>
</header><footer>
<div class="MainWrapper">
<ul>
<li>© Copyright 2013</li>
If I inspect using firebug I do see a gap in the code:
</nav>
</header>
<footer>
<div class="MainWrapper">
<ul>
Furthermore if I try to edit the code in firebug I get a weird entity number where the gap appears: 
:
</nav>
</header><footer>
<div class="MainWrapper">
<ul>
This has to do something with php because if I write the HTML of the header and the footer straight in the page the gap disappears:
Any ideas? Thanks.
As Per Why is  appearing in my HTML?
it may have a Simple Fix!
The character in question  is the Unicode Character 'ZERO WIDTH NO-BREAK SPACE' (U+FEFF) attached to your code on a copy/paste or during a faulty Save its so simple to fix that, just open that file by notepad++ and step follow -->
Encoding->Encode in UTF-8 without BOM
. then save that. It work for me as well!