An <iframe> that looks like it is a part of the containing document:
Note: The seamless attribute of the <iframe> tag is supported only in Chrome and Safari 6.
The seamless attribute is a boolean attribute.
When present, it specifies that the <iframe> should look like it is a part of the containing document (no borders or scrollbars).
The seamless attribute is new in HTML5.
In XHTML, attribute minimization is forbidden, and the seamless attribute must be defined as <iframe seamless="seamless">.
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