call design area  Mage::app()->loadArea('frontend'); in php file outside magento.

<?php
include_once "app/Mage.php";
umask(0);
Mage::app()->loadArea('frontend');

$layout = Mage::getSingleton('core/layout');

//load default xml layout handle and generate blocks
$layout->getUpdate()->load('default');
$layout->generateXml()->generateBlocks();

//get the loaded head and header blocks and output
$headBlock = $layout->getBlock('head');
$headerBlock = $layout->getBlock('header');
echo $headBlock->toHtml() . $headerBlock->toHtml();
get footer

$footerBlock = $layout->getBlock('footer');
echo $footerBlock->toHtml();

Refer :- My Answer On Magento Stackexchange


Easy One...!!!