Iframe In Internet Explorer Quirks Mode Will Not Render At 100% Width

I have an iframe which is absolutely poitioned at the top of a page. This is actually a header that is added to customer's webpages, as such DOCTYPEs will vary and thus so will the

Solution 1:

Adding this CSS fixes it (in IE8/IE7 Quirks Mode):

html {
    margin: 0;
    padding: 0
}

It's surely safe to universally include that - I imagine virtually zero sites are relying on the <html> element having margin or padding.

Some sites apply a non-zero margin or padding to <body>, but never to <html>.