How to change style of a included html file inside <object> tag ?

How to change style of a included html file inside <object> tag ?

I want to change the style of a html file I get from the web when including it inside <Object> tag.

My purpose is to hange the display of web page such as https://clients3.google.com/cast/chromecast/home
to make it full screen and discard the dark veil, so on ....

Then my file could be :

<html>
<body>
<object id="file" data=" https://clients3.google.com/cast/chromecast/home" type="text/html" style="width: 100%; height: 100%">
</body>
</html>

How can I get inside the code to restyle the page as I want by jquery css?
When you use developer tools (chrome), the code appears as element <#document> under <object>.

Thanks !