Code:
<style type='text/css'>
/* Fix the iframe */
html, body, iframe, table, tr, td {margin: 0; padding: 0;}
html, body, iframe, table, #content {height: 100%; width: 100%;}
table {border-collapse: collapse;}
iframe {border: 0;}
/* I finished, cookie now?*/
</style>
</head>
<body>
<table>
<tr><td id="content">
<iframe src="http://www.example.com" />
</td></tr>
</table>
This will fill a website into another website with border or padding.
You can modify the code to make it more like what you want.