Bootstrap/docs/4.0/utilities/responsive-helpers.md

---
layout: docs
title: Responsive helpers
description: Create responsive video or slideshow embeds based on the width of the parent by creating an intrinsic ratio that scales on any device.
group: utilities
toc: true
---

## Responsive embeds

Rules are directly applied to `<iframe>`, `<embed>`, `<video>`, and `<object>` elements; optionally use an explicit descendant class `.embed-responsive-item` when you want to match the styling for other attributes.

**Pro-Tip!** You don't need to include `frameborder="0"` in your `<iframe>`s as we override that for you.

{% example html %}
<div class="embed-responsive embed-responsive-16by9">
  <iframe class="embed-responsive-item" src="https://www.youtube.com/embed/zpOULjyy-n8?rel=0" allowfullscreen></iframe>
</div>
{% endexample %}

Aspect ratios can be customized with modifier classes.

{% highlight html %}
<!-- 21:9 aspect ratio -->
<div class="embed-responsive embed-responsive-21by9">
  <iframe class="embed-responsive-item" src="..."></iframe>
</div>

<!-- 16:9 aspect ratio -->
<div class="embed-responsive embed-responsive-16by9">
  <iframe class="embed-responsive-item" src="..."></iframe>
</div>

<!-- 4:3 aspect ratio -->
<div class="embed-responsive embed-responsive-4by3">
  <iframe class="embed-responsive-item" src="..."></iframe>
</div>

<!-- 1:1 aspect ratio -->
<div class="embed-responsive embed-responsive-1by1">
  <iframe class="embed-responsive-item" src="..."></iframe>
</div>
{% endhighlight %}

## Responsive floats

These utility classes float an element to the left or right, or disable floating, based on the current viewport size using the [CSS `float` property](https://developer.mozilla.org/en-US/docs/Web/CSS/float). `!important` is included to avoid specificity issues. These use the same viewport width breakpoints as the grid system.

Two similar non-responsive Sass mixins (`float-left` and `float-right`) are also available.

{% example html %}
<div class="float-left">Float left on all viewport sizes</div><br>
<div class="float-right">Float right on all viewport sizes</div><br>
<div class="float-none">Don't float on all viewport sizes</div><br>

<div class="float-sm-left">Float left on viewports sized SM (small) or wider</div><br>
<div class="float-md-left">Float left on viewports sized MD (medium) or wider</div><br>
<div class="float-lg-left">Float left on viewports sized LG (large) or wider</div><br>
<div class="float-xl-left">Float left on viewports sized XL (extra-large) or wider</div><br>
{% endexample %}

{% highlight scss %}
// Related simple non-responsive mixins
.element {
  @include float-left;
}
.another-element {
  @include float-right;
}
{% endhighlight %}