Are you aware that the follow attributes have now been deprecated from use within the <iframe>?
alignframeborderlongdescmarginheightmarginwidthscrolling
But what happens when you want to remove the default border from an iframe? The best option is some simple CSS:
iframe {
border: 1px solid #000;
}
Using the title attribute
While the title attribute should be avoided in most cases, it can be applied to the <iframe> element to label its content for assistive technologies.
<iframe title="Concise description of embedded content">
</iframe>
The seamless attribute
Before the seamless attribute was dropped, it was intended to make the <iframe> “seamlessly” look like it is part of the parent document. The HTML5 spec stated:
“it indicates that the iframe element’s browsing context is to be rendered in a manner that makes it appear to be part of the containing document (seamlessly included in the parent document).”