Iframe creates extra space below

Issue

Why does an iframe add extra space under its element? Look at this weird behavior:

.border {
    background: red;
    width: 300px;
    height: 200px;
    border: 1px solid green;
    overflow: visible;
    margin: 0;
    padding: 0;
}

.border iframe {
    border: none;
    width: 300px;
    height: 100px;
    margin: 0;
    padding: 0;
    opacity: 0.8;
}

.border .lower {
    height: 100px;
    margin: 0;
    padding: 0;
    background: blue;
    opacity: 0.8;
}

<div class="border">
  <iframe src="https://example.com"></iframe>
  <div class="lower"></div>
</div>

How to work around?

Solution

Add display:block; to your Iframe style like so:

.border iframe {
    border: none;
    width: 300px;
    height: 100px;
    margin: 0;
    padding: 0;
    opacity: 0.8;
    display:block; /* Add this */
}

Iframe is an Inline Frame, meaning that it is an inline element, which like the img tag, can have issues with whitespace. Setting display:block; on it turns the Iframe into a block element (like a div), which will remove the whitespace issue.

Answered By - wickywills