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30-seconds-of-code/snippets/constant-width-to-height-ratio.md
2018-02-28 05:36:01 +10:00

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Markdown

### Constant width to height ratio
Given an element of variable width, it will ensure its height remains proportionate in a responsive fashion
(i.e., its width to height ratio remains constant).
#### HTML
```html
<div class="constant-width-to-height-ratio"></div>
```
#### CSS
```css
.constant-width-to-height-ratio {
background: #333;
width: 50%;
padding-top: 50%;
}
```
#### Demo
Resize your browser window to see the proportion of the element remain the same.
<div class="snippet-demo">
<div class="snippet-demo__constant-width-to-height-ratio"></div>
</div>
<style>
.snippet-demo__constant-width-to-height-ratio {
background: #333;
width: 50%;
padding-top: 50%;
}
</style>
#### Explanation
`padding-top` and `padding-bottom` can be used as an alternative to `height` such that the percentage value
causes an element's height to become a percentage of its parent's width, i.e. `50%` means the height will be 50% of the parent element's width, which means it acts the same as `width`. This allows its proportion to remain constant.
#### Browser support
<span class="snippet__support-note">⚠️ `padding-top` pushes any content within the element to the bottom.</span>