Sorry for the really dumb title but I dont know how else to phrase it.
Well I have my index.php which provides a nice frame layout for my HTMl using CSS and divs. Each page i.e the header, navigation bar, footer etc. are added in the div via PHP include(..).
Here is my index.php:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Test</title>
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<style type="text/css" media="screen">
html, body{
padding: 0;
margin: 0 auto;
height: 100%;
}
#header {
width: 100%;
height: 15%;
background-color: green;
}
#navbar {
float: left;
width: 20%;
height: 70%;
background-color: red;
}
#content {
float: right;
width: 80%;
height: 70%;
background-color: blue;
}
#footer {
clear: both;
width: 100%;
height: 15%;
background-color: yellow;
}
</style>
</head>
<body>
<div id="header">
<?php
include("header.html");
?>
</div>
<div id="navbar">
<?php
include("nav.php");
?>
</div>
<div id="content">
<?php
include("home.html");
?>
</div>
<div id="footer">
<?php
include("footer.php");
?>
</div>
</body>
</html>
Now look here in <body> tag of index.php:
<div id="header">
<?php
include("header.html");
?>
</div>
this piece will of course add my header.html which looks like this:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Title</title>
<meta http-equiv="content-type"
content="text/html; charset=iso-8859-1"
/>
</head>
<body>
<p align="center">TITLE PAGE</p>
</body>
</html>
producing this:

See that white bar at the top of TITLE PAGE? Well thats not meant to be there...
And if I add anything to my actual <body> of header.html i.e:
<body>
Hello
<p align="center">TITLE PAGE</p>
</body>
Notice how the white bar disappears and web browser does not have the scrollbar anymore? everything works just peachy - well besides that random text needed to clear the white bar:

So basically my question is why is this happening and how would I go about fixing it?
UPDATE:
Fixed white bar by setting
margin in header.html to 0 (+1 @Imperative):
<p align="center" style="margin: 0;">TITLE PAGE</p>
Now I would just like to know wether or not I am doing right by including DOCTYPE html header title etc tags each time I create a new html? Or should I only do this once in my index.php? If so than how would I make my header.html pass validation at http://validator.w3.org/