Responsive video iframes (keeping aspect ratio) with only CSS? - html

Question

I usually use a similar solution to this one. Something like:
.wrapper {
position: relative;
width: 100%;
height: 0;
padding-bottom: 56.25%;
}
.wrapper iframe {
position:absolute;
left: 0;
top: 0;
height: 100%;
width: 100%;
}
But this time I have no access to the HTML or JavaScript code so I can't use a wrapper to prevent the height:0.
Is there a way to make an iframe responsive (and to keep the ratio) with only CSS?
Tried this (works with the iframe but not with its content):
iframe {
width: 100%;
background: red;
height: 0;
padding-bottom: 33%;
}
fiddle
Any thoughts? No need to support old browsers so even a CSS3 solution would be great.

Answer 1

Here is a Fiddle for a solution, that is based on a CSS2 secret: https://jsfiddle.net/59f9uc5e/2/
<div class="aspect-ratio">
<iframe src="" width="550" height="275" frameborder="0"></iframe>
</div>
<style>
/* This element defines the size the iframe will take.
In this example we want to have a ratio of 25:14 */
.aspect-ratio {
position: relative;
width: 100%;
height: 0;
padding-bottom: 56.25%; /* The height of the item will now be 56.25% of the width. */
}
/* Adjust the iframe so it's rendered in the outer-width and outer-height of it's parent */
.aspect-ratio iframe {
position: absolute;
width: 100%;
height: 100%;
left: 0;
top: 0;
}
</style>
It is explained by how percentage-values for padding are handled:
The percentage is calculated with respect to the width of the generated box's containing block, even for 'padding-top' and 'padding-bottom'.
https://www.w3.org/TR/CSS2/box.html#padding-properties

Answer 2

Use the new CSS viewport units vw and vh (viewport width / viewport height)
FIDDLE
iframe {
width: 100vw;
height: 56.25vw; /* 100/56.25 = 560/315 = 1.778 */
background:red;
}
Browser support is also good: IE9+ (caniuse)

Answer 3

Calc function makes it much more readable:
.iframe-video {
width: 755px;
height: 424px;
max-width: 100%;
max-height: calc((100vw - 40px) / (16/9));
}
width and height is size for desktop and also fallback to ancient browsers
40px is margin (20 px between iframe border and viewport border on both sides)
16/9 is ratio of video (if you have edge-to-edge player)

Answer 4

With css aspect-ratio it's easy.
iframe {
height: auto;
width: 100%;
aspect-ratio: 16 / 9;
}

Answer 5

<div>
<div style="position:relative;padding-top:56.25%;">
<iframe src="https://www.youtube.com/embed/nckseQJ1Nlg" frameborder="0" allowfullscreen
style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe>
</div>
</div>
Please add this styling to the web url content you are trying to load. It will keep the 16:9 aspect ratio.

Answer 6

This is kind of hackish however you can use images to preserve the aspect ratio of a video. For example I went to paint and saved an image of 1280 x 720 resolution to use for a 16:9 aspect ratio (in here I will just grab a blank image off the internet somewhere).
This works because if you change the width of an image while leaving height auto, vise-versa the image will automatically scale - keeping proportions.
img {
display: block;
height: auto;
width: 100%;
}
iframe {
height: 100%;
left: 0;
position: absolute;
top: 0;
width: 100%;
}
.wrapper {
float: left;
position: relative;
}
<div class="wrapper">
<img src="http://www.solidbackgrounds.com/images/1280x720/1280x720-ghost-white-solid-color-background.jpg" alt=""/>
<iframe width="560" height="315" src="https://www.youtube.com/embed/HkMNOlYcpHg" frameborder="0" allowfullscreen></iframe>
</div>

Answer 7

I had the same issue and this worked for me:
.wrapper iframe{
width: 100%; /* This Forces video to 100% of parent's width */
height:unset; /* This Overwrites the height attribute of Youtube's embed code */
aspect-ratio: 16 / 9; /* This adjusts video height to keep the desired aspect ratio*/
}