So I have a header file:
<html>
<head>
   <link href="/design_header.css" rel="stylesheet" type="text/css" />
</head>
<body>
   content
</body>
</html>
And I want to place this header in my file
  <!DOCTYPE html>
    <html xmlns="http://www.w3.org/1999/xhtml" lang="en">
     <head>
     meta tags etc.
    </head>
    <body> 
      <div id="container_big">
       <?php include 'header_login.php'; ?>
        content
      </div>
    </body>
    </html>
The problem is now I have regular <html>, <head>, <body> tags inside the <body> tag of my webpage. In the html validator I receive errors like
Stray start tag html. Stray end tag head. An body start tag seen but an element of th
e same type was already open.
How to do it properly? Btw. I also place a footer to the bottom of the webpage the same way.