Customizing a Simple Auto reply Email Problem

Hi all, I am very new to Php and I have done some searching around and I cant find an answer to this. So I am hoping some kind person might be able to help me.

I have managed to get my auto reply working, but I want to be able to customize the actual email sent (fonts, colours, etc.) rather than just plain black and white text.

Here is my code so far:


<?php
$contact_name = $_POST['name'];
$contact_email = $_POST['email'];
$contact_subject = $_POST['subject'];
$contact_message = $_POST['message'];



if( $contact_name == true )
{
	$sender = $contact_email;
	$receiver = "myemailhost.com";
	$client_ip = $_SERVER['REMOTE_ADDR'];
	$email_body = "Name: $contact_name 
Email: $sender 
Subject: $contact_subject 
Message: $contact_message 
IP: $client_ip 
From Industrial Placement Website";		
	$extra = "From: $sender
" . "Reply-To: $sender 
" . "X-Mailer: PHP/" . phpversion();

	if( mail( $receiver, "Flash Contact Form - $subject", $email_body, $extra ) ) 
	{
		echo "success=yes";
	}
	else
	{
		echo "success=no";
	}
}
// The Reply
$email = $_POST['email']; 
$header = "myemail.com";
$subject = 'Submission'; // change subject
$message = 'This is a confirmation that we have recieved your message, and we will be in contact with you soon regarding your enquiry. 

Thanks for your interest.

Bailey

'; // change text
mail($email, $subject, $message, 'From: '.$receiver.''); // send another one out
?>

I am trying to work out how I can customize my auto reply, but I am really struggling. Any help would be greatly appreciated.

Sliilvia