I want to create a responsive div that can change its width/height as the window's width changes.
Are there any CSS rules that would allow the height to change according to the width, while maintaining its aspect ratio?
I know I can do this via JavaScript, but I would prefer using only CSS.
Just create a wrapper <div> with a percentage value for padding-bottom, like this:
.demoWrapper {
padding: 10px;
background: white;
box-sizing: border-box;
resize: horizontal;
border: 1px dashed;
overflow: auto;
max-width: 100%;
height: calc(100vh - 16px);
}
div {
width: 100%;
padding-bottom: 75%;
background: gold; /** <-- For the demo **/
}<div class="demoWrapper">
<div></div>
</div>It will result in a <div> with height equal to 75% of the width of its container (a 4:3 aspect ratio).
This relies on the fact that for padding :
The percentage is calculated with respect to the width of the generated box's containing block [...] (source: w3.org, emphasis mine)
Padding-bottom values for other aspect ratios and 100% width :
aspect ratio | padding-bottom value
--------------|----------------------
16:9 | 56.25%
4:3 | 75%
3:2 | 66.66%
8:5 | 62.5%
Placing content in the div :
In order to keep the aspect ratio of the div and prevent its content from stretching it, you need to add an absolutely positioned child and stretch it to the edges of the wrapper with:
div.stretchy-wrapper {
position: relative;
}
div.stretchy-wrapper > div {
position: absolute;
top: 0; bottom: 0; left: 0; right: 0;
}
Here's a demo and another more in depth demo
There are several ways to specify a fixed aspect ratio on an element like a div, here are 2 of them:
aspect-ratio CSS propertydiv {
aspect-ratio: 1 / 1;
width: 50%;
background: teal;
}<div>aspect-ratio: 1 / 1;</div>This is the most simple and flexible solution. It directly specifies a fixed width to height (or height to width) aspect ratio for an element. This means you can also specify an aspect ratio according to the elements height.
It doesn't rely on the parent width (like the padding technique) or the viewport size (like the following vw unit technique) it relies on the element's own width or height More info on MDN. That is what make it so powerfull compared to other workarounds.
This is a modern property (2021). All modern browsers support it, see caniuse for precise browser support.
Here are a few examples with different aspect ratios :
.ar-1-1 {aspect-ratio: 1 / 1;}
.ar-3-2 {aspect-ratio: 3 / 2;}
.ar-4-3 {aspect-ratio: 4 / 3;}
.ar-16-9 {aspect-ratio: 16 / 9;}
.ar-2-3 {aspect-ratio: 2 / 3;}
.ar-3-4 {aspect-ratio: 3 / 4;}
.ar-9-16 {aspect-ratio: 9 / 16;}
/** For the demo : **/
body {
display:flex;
flex-wrap:wrap;
align-items:flex-start;
}
div {
background: teal;
width: 23%;
margin:1%;
padding:20px 0;
box-sizing: border-box;
color:#fff;
text-align:center;
}<div class="ar-1-1">aspect-ratio: 1 / 1;</div>
<div class="ar-3-2">aspect-ratio: 3 / 2;</div>
<div class="ar-4-3">aspect-ratio: 4 / 3;</div>
<div class="ar-16-9">aspect-ratio: 16 / 9;</div>
<div class="ar-2-3">aspect-ratio: 2 / 3;</div>
<div class="ar-3-4">aspect-ratio: 3 / 4;</div>
<div class="ar-9-16">aspect-ratio: 9 / 16;</div>vw units:You can use vw units for both the width and height of the element. This allows the element's aspect ratio to be preserved, based on the viewport width.
vw : 1/100th of the width of the viewport. [MDN]
Alternatively, you can also use vh for viewport height, or even vmin/vmax to use the lesser/greater of the viewport dimensions (discussion here).
Example: 1:1 aspect ratio
div {
width: 20vw;
height: 20vw;
background: gold;
}<div></div>For other aspect ratios, you can use the following table to calculate the value for height according to the width of the element :
aspect ratio | multiply width by
-----------------------------------
1:1 | 1
1:3 | 3
4:3 | 0.75
16:9 | 0.5625
body {
display: flex;
flex-wrap: wrap;
justify-content: space-between;
}
div {
width: 23vw;
height: 23vw;
margin: 0.5vw auto;
background: gold;
}<div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div>Here is a Fiddle with this demo and here is a solution to make a responsive grid of squares with verticaly and horizontaly centered content.
Browser support for vh/vw units is IE9+ see canIuse for more info
Use the aspect-ratio CSS property
<div class='demo'></div>
.demo {
background: black;
width: 500px;
aspect-ratio: 4/3;
}
aspec-ratio. Instead you can use something like height: calc(100vw * 4 / 3);
This answer was written before aspect-ratio was implemented in CSS. That's what you should use today.
Original answer
I stumbled upon what I consider a smart solution for this problem, using <svg> and display:grid.
A display:grid element allows you to occupy the same space with two (or more) of its children, using the same grid-area.
This means means they are all flow content, overlapped, and out of the box the taller one sets the ratio.
One of them will be an <svg> in charge of setting the ratio. The other, actual content. If actual content is short and never fills up the entire ratio (and you just want it centered in a space with this ratio), simply center it (see first runnable snippet below).
<div class="ratio">
<svg viewBox="0 0 1 1"></svg>
<div>
I'm square
</div>
</div>
.ratio {
display: grid;
}
.ratio > * {
grid-area: 1/1;
}
Set <svg>s ratio to whatever you want:
<svg viewBox="0 0 4 3"></svg><svg viewBox="0 0 16 9"></svg>.ratio {
display: grid;
}
.ratio > * {
grid-area: 1/1;
}
/* below code NOT needed for setting the ratio
* I just wanted to mark it visually
* and center contents
*/
.ratio div {
border: 1px solid red;
display: flex;
align-items: center;
justify-content: center;
}<div class="ratio">
<svg viewBox="0 0 7 1"></svg>
<div>
Fixed ratio 7:1
</div>
</div>If you need a solution where the content element has more content you want confined into a scrollable area with desired ratio, set position:relative on the parent and position:absolute; height:100%; overflow-y: auto; on the content, allowing the flow content element (the <svg>) to set the size, therefore the ratio.
.ratio {
display: grid;
position: relative;
}
.ratio > * {
grid-area: 1/1;
}
.ratio > div {
height: 100%;
overflow-y: auto;
position: absolute;
/* the rest is not needed */
border: 1px solid red;
padding: 0 1rem;
}<div class="ratio">
<svg viewBox="0 0 7 2"></svg>
<div>
<h1>Fixed ratio 7:2</h1>
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<p>Mauris a diam maecenas sed enim ut sem. In hendrerit gravida rutrum quisque. Amet dictum sit amet justo donec enim diam. Diam vulputate ut pharetra sit amet aliquam id. Urna porttitor rhoncus dolor purus non enim praesent. Purus in massa tempor nec feugiat nisl pretium. Sagittis vitae et leo duis ut. Facilisi nullam vehicula ipsum a arcu cursus vitae congue mauris. Volutpat odio facilisis mauris sit amet massa vitae tortor condimentum. Aliquam purus sit amet luctus venenatis lectus magna. Sit amet purus gravida quis blandit turpis. Enim eu turpis egestas pretium aenean. Consequat mauris nunc congue nisi. Nunc sed id semper risus in hendrerit gravida rutrum. Ante metus dictum at tempor. Blandit massa enim nec dui nunc mattis enim ut.
</div>
</div>As @emjay noted in a comment below, the ratio svg can be placed in one of the parent's pseudo-elements, as long as it's properly encoded:
.three-squares {
display: grid;
border: 1px solid red;
}
.three-squares > *, .three-squares:before {
grid-area: 1/1;
}
.three-squares:before {
content: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 3 1'%3E%3C/svg%3E");
line-height: 0;
}<div class="three-squares">
<div>I'm 3:1</div>
</div>When used inside a pseudo-element, the <svg> becomes a replaced element which, by default, sits on a baseline of variable height (4px in Chrome, 3.5px in Firefox). The height of the baseline varies according to line-height, which is why we need to set line-height: 0 on the pseudo to get an accurate ratio. More details here.
I personally prefer the version where the <svg> is placed in markup, as I can have a single class (.ratio) dealing with containers of various ratios (as opposed to having a class for each individual ratio I might need).
I've found a way to do this using CSS, but you have to be careful as it may change depending on the flow of your own web site. I've done it in order to embed video with a constant aspect ratio within a fluid width portion of my web site.
Say you have an embedded video like this:
<object>
<param ... /><param ... />...
<embed src="..." ...</embed>
</object>
You could then place this all inside a div with a "video" class. This video class will probably be the fluid element in your website such that, by itself, it has no direct height constraints, but when you resize the browser it will change in width according to the flow of the web site. This would be the element you are probably trying to get your embedded video in while maintaining a certain aspect ratio of the video.
In order to do this, I put an image before the embedded object within the "video" class div.
!!! The important part is that the image has the correct aspect ratio you wish to maintain. Also, make sure the size of the image is AT LEAST as big as the smallest you expect the video (or whatever you are maintaining the A.R. of) to get based on your layout. This will avoid any potential issues in the resolution of the image when it is percentage-resized. For example, if you wanted to maintain an aspect ratio of 3:2, don't just use a 3px by 2px image. It may work under some circumstances, but I haven't tested it, and it would probably be a good idea to avoid.
You should probably already have a minimum width like this defined for fluid elements of your web site. If not, it is a good idea to do so in order to avoid chopping elements off or having overlap when the browser window gets too small. It is better to have a scroll bar at some point. The smallest in width a web page should get is somewhere around ~600px (including any fixed width columns) because screen resolutions don't come smaller unless you are dealing with phone-friendly sites. !!!
I use a completely transparent png but I don't really think it ends up mattering if you do it right. Like this:
<div class="video">
<img class="maintainaspectratio" src="maintainaspectratio.png" />
<object>
<param ... /><param ... />...
<embed src="..." ...</embed>
</object>
</div>
Now you should be able to add CSS similar to the following:
div.video { ...; position: relative; }
div.video img.maintainaspectratio { width: 100%; }
div.video object { position: absolute; top: 0px; left: 0px; width: 100%; height: 100%; }
div.video embed {width: 100%; height: 100%; }
Make sure you also remove any explicit height or width declaration within the object and embed tags that usually come with copy/pasted embed code.
The way it works depends on the position properties of the video class element and the item you want have maintain a certain aspect ratio. It takes advantage of the way an image will maintain its proper aspect ratio when resized in an element. It tells whatever else is in video class element to take full-advantage of the real estate provided by the dynamic image by forcing its width/height to 100% of the video class element being adjusted by the image.
Pretty cool, eh?
You might have to play around with it a bit to get it to work with your own design, but this actually works surprisingly well for me. The general concept is there.
Elliot inspired me to this solution - thanks:
aspectratio.png is a completely transparent PNG-file with the size of your preferred aspect-ratio, in my case 30x10 pixels.
<div class="eyecatcher">
<img src="/img/aspectratio.png"/>
</div>
.eyecatcher img {
width: 100%;
background-repeat: no-repeat;
background-size: 100% 100%;
background-image: url(../img/autoresized-picture.jpg);
}
Please note: background-size is a css3-feature which might not work with your target-browsers. You may check interoperability (f.e. on caniuse.com).
As @web-tiki already show a way to use vh/vw, I also need a way to center in the screen, here is a snippet code for 9:16 portrait.
.container {
width: 100vw;
height: calc(100vw * 16 / 9);
transform: translateY(calc((100vw * 16 / 9 - 100vh) / -2));
}
translateY will keep this center in the screen. calc(100vw * 16 / 9) is expected height for 9/16.(100vw * 16 / 9 - 100vh) is overflow height, so, pull up overflow height/2 will keep it center on screen.
For landscape, and keep 16:9, you show use
.container {
width: 100vw;
height: calc(100vw * 9 / 16);
transform: translateY(calc((100vw * 9 / 16 - 100vh) / -2));
}
The ratio 9/16 is ease to change, no need to predefined 100:56.25 or 100:75.If you want to ensure height first, you should switch width and height, e.g. height:100vh;width: calc(100vh * 9 / 16) for 9:16 portrait.
If you want to adapted for different screen size, you may also interest
@media (orientation: portrait)/@media (orientation: landscape)
portrait/landscape to change the ratio.As stated in here on w3schools.com and somewhat reiterated in this accepted answer, padding values as percentages (emphasis mine):
Specifies the padding in percent of the width of the containing element
Ergo, a correct example of a responsive DIV that keeps a 16:9 aspect ratio is as follows:
CSS
.parent {
position: relative;
width: 100%;
}
.child {
position: relative;
padding-bottom: calc(100% * 9 / 16);
}
.child > div {
position: absolute;
top: 0;
bottom: 0;
left: 0;
right: 0;
}
HTML
<div class="parent">
<div class="child">
<div>Aspect is kept when resizing</div>
</div>
</div>
Use the CSS aspect-ratio property
https://caniuse.com/#search=aspect-ratio
If you are interested how to use it - take a look at the below super easy example
.yourClass {
aspect-ratio: 4/3;
}
To add to Web_Designer's answer, the <div> will have a height (entirely made up of bottom padding) of 75% of the width of it's containing element. Here's a good summary: http://mattsnider.com/css-using-percent-for-margin-and-padding/. I'm not sure why this should be so, but that's how it is.
If you want your div to be a width other than 100%, you need another wrapping div on which to set the width:
div.ar-outer{
width: 60%; /* container; whatever width you want */
margin: 0 auto; /* centered if you like */
}
div.ar {
width:100%; /* 100% of width of container */
padding-bottom: 75%; /* 75% of width of container */
position:relative;
}
div.ar-inner {
position: absolute;
top: 0; bottom: 0; left: 0; right: 0;
}
I used something similar to Elliot's image trick recently to allow me to use CSS media queries to serve a different logo file depending on device resolution, but still scale proportionally as an <img> would naturally do (I set the logo as background image to a transparent .png with the correct aspect ratio). But Web_Designer's solution would save me an http request.
This is an improvement on web_designer's answer:
.box {
margin-top: 1em;
margin-bottom: 1em;
background-color: #CCC;
}
.fixed-ar::before {
content: "";
float: left;
width: 1px;
margin-left: -1px;
}
.fixed-ar::after {
content: "";
display: table;
clear: both;
}
.fixed-ar-16-9::before {
padding-top: 56.25%;
}
.fixed-ar-3-2::before {
padding-top: 66.66%;
}
.fixed-ar-4-3::before {
padding-top: 75%;
}
.fixed-ar-1-1::before {
padding-top: 100%;
}
.width-50 {
display: inline-block;
width: 50%;
}
.width-20 {
display: inline-block;
width: 20%;
}<div class="box fixed-ar fixed-ar-16-9">16:9 full width</div>
<hr>
<div class="box fixed-ar fixed-ar-16-9 width-50">16:9</div>
<hr>
<div class="box fixed-ar fixed-ar-16-9 width-20">16:9</div>
<div class="box fixed-ar fixed-ar-3-2 width-20">3:2</div>
<div class="box fixed-ar fixed-ar-4-3 width-20">4:3</div>
<div class="box fixed-ar fixed-ar-1-1 width-20">1:1</div>
<hr>
<div class="box fixed-ar fixed-ar-16-9 width-20">16:9</div>
<div class="box fixed-ar fixed-ar-16-9 width-50">16:9</div>
You can use an svg. Make the container/wrapper position relative, put the svg first as staticly positioned and then put absolutely positioned content (top: 0; left:0; right:0; bottom:0;)
Example with 16:9 proportions:
image.svg: (can be inlined in src)
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 9" width="16" height="9"/>
CSS:
.container {
position: relative;
}
.content {
position: absolute;
top:0; left:0; right:0; bottom:0;
}
HTML:
<div class="container">
<img style="width: 100%" src="image.svg" />
<div class="content"></div>
</div>
Note that inline svg doesn't seem to work, but you can urlencode the svg and embed it in img src attribute like this:
<img src="data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%220%200%2016%209%22%20width%3D%2216%22%20height%3D%229%22%2F%3E" style="width: 100%;" />
Here's how I do it :
[data-aspect-ratio] {
display: block;
max-width: 100%;
position: relative;
}
[data-aspect-ratio]:before {
content: '';
display: block;
}
[data-aspect-ratio] > * {
display: block;
height: 100%;
left: 0;
position: absolute;
top: 0;
width: 100%;
}
[data-aspect-ratio="3:1"]:before {
padding-top: 33.33%;
}
[data-aspect-ratio="2:1"]:before {
padding-top: 50%;
}
[data-aspect-ratio="16:9"]:before {
padding-top: 56.25%;
}
[data-aspect-ratio="3:2"]:before {
padding-top: 66.66%;
}
[data-aspect-ratio="4:3"]:before {
padding-top: 75%;
}
[data-aspect-ratio="1:1"]:before {
padding-top: 100%;
}
[data-aspect-ratio="3:4"]:before {
padding-top: 133.33%;
}
[data-aspect-ratio="2:3"]:before {
padding-top: 150%;
}
[data-aspect-ratio="9:16"]:before {
padding-top: 177.77%;
}
[data-aspect-ratio="1:2"]:before {
padding-top: 200%;
}
[data-aspect-ratio="1:3"]:before {
padding-top: 300%;
}
For example :
<div data-aspect-ratio="16:9"><iframe ...></iframe></div>
[data-aspect-ratio] attribute selector is available to you in CSS.
Basing on your solutions I've made some trick:
When you use it, your HTML will be only
<div data-keep-ratio="75%">
<div>Main content</div>
</div>
To use it this way make: CSS:
*[data-keep-ratio] {
display: block;
width: 100%;
position: relative;
}
*[data-keep-ratio] > * {
position: absolute;
left: 0;
right: 0;
top: 0;
bottom: 0;
}
and js (jQuery)
$('*[data-keep-ratio]').each(function(){
var ratio = $(this).data('keep-ratio');
$(this).css('padding-bottom', ratio);
});
And having this you just set attr data-keep-ratio to height/width and that's it.
I have found some more fresh way to solve this case. This solution is a descendant of a any padding-bottom method, but without any position: absolute children, just using display: grid; and pseudo element.
Here we have .ratio::before with good old padding-bottom: XX% and grid-area: 1 / 1 / 1 / 1;, which forces the pseudo element to keep the position in grid. Although here we have width: 0; to prevent overflowing main element by this one (we cold use z-index here, but this one is shorter).
And our main element .ratio > *:first-child has the same position as .ratio::before, which is grid-area: 1 / 1 / 1 / 1;, so they both shares the same grid cell place. Now we can put any content in our div, and the pseudo element is the one who determines the width/height ratio. More about grid-area.
.ratio {
display: grid;
grid-template-columns: 1fr;
max-width: 200px; /* just for instance, can be 100% and depends on parent */
}
.ratio::before {
content: '';
width: 0;
padding-bottom: calc(100% / (16/9)); /* here you can place any ratio */
grid-area: 1 / 1 / 1 / 1;
}
.ratio>*:first-child {
grid-area: 1 / 1 / 1 / 1; /* the same as ::before */
background: rgba(0, 0, 0, 0.1); /* just for instance */
}<div class="ratio">
<div>16/9</div>
</div>Although you can use CSS val and place you ratio in HTML using style attribute. Works with display: inline-grid as well.
.ratio {
display: inline-grid;
grid-template-columns: 1fr;
width: 200px; /* just for instance, can be 100% and depends on parent */
margin-right: 10px; /* just for instance */
}
.ratio::before {
content: '';
width: 0;
padding-bottom: calc(100% / (var(--r))); /* here you can place any ratio */
grid-area: 1 / 1 / 1 / 1;
}
.ratio>*:first-child {
grid-area: 1 / 1 / 1 / 1; /* the same as ::before */
background: rgba(0, 0, 0, 0.1); /* just for instance */
}<div class="ratio" style="--r: 4/3;">
<div>4/3</div>
</div>
<div class="ratio" style="--r: 16/9;">
<div>16/9</div>
</div>
While most answers are very cool, most of them require to have an image already sized correctly... Other solutions only work for a width and do not care of the height available, but sometimes you want to fit the content in a certain height too.
I've tried to couple them together to bring a fully portable and re-sizable solution... The trick is to use to auto scaling of an image but use an inline svg element instead of using a pre-rendered image or any form of second HTTP request...
div.holder{
background-color:red;
display:inline-block;
height:100px;
width:400px;
}
svg, img{
background-color:blue;
display:block;
height:auto;
width:auto;
max-width:100%;
max-height:100%;
}
.content_sizer{
position:relative;
display:inline-block;
height:100%;
}
.content{
position:absolute;
top:0;
bottom:0;
left:0;
right:0;
background-color:rgba(155,255,0,0.5);
}<div class="holder">
<div class="content_sizer">
<svg width=10000 height=5000 />
<div class="content">
</div>
</div>
</div>Notice that I have used big values in the width and height attributes of the SVG, as it needs to be bigger than the maximum expected size as it can only shrink. The example makes the div's ratio 10:5
If you want to fit a square inside the viewport on either portrait or landscape view (as big as possible, but nothing sticking outside), switch between using vw/vh on orientation portrait/landscape:
@media (orientation:portrait ) {
.square {
width :100vw;
height:100vw;
}
}
@media (orientation:landscape) {
.square {
width :100vh;
height:100vh;
}
}
You can achieve that by using SVG.
It depends on a case, but in some it is really usefull. As an example - you can set background-image without setting fixed height or use it to embed youtube <iframe> with ratio 16:9 and position:absolute etc.
For 3:2 ratio set viewBox="0 0 3 2" and so on.
Example:
div{
background-color:red
}
svg{
width:100%;
display:block;
visibility:hidden
}
.demo-1{width:35%}
.demo-2{width:20%}<div class="demo-1">
<svg viewBox="0 0 3 2"></svg>
</div>
<hr>
<div class="demo-2">
<svg viewBox="0 0 3 2"></svg>
</div>
I'd like to share my solution, where I have an img-tag filling a certain aspect ratio. I couldn't use background because of lack of support of the CMS and I'd not prefer to use a style tag like so: <img style="background:url(...)" />. Also, the width is 100%, so it doesn't need to be set at a fixed size as in some of the solutions. It will scale responsively!
.wrapper {
width: 50%;
}
.image-container {
position: relative;
width: 100%;
}
.image-container::before {
content: "";
display: block;
}
.image-container img {
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
object-fit: cover;
}
.ratio-4-3::before {
padding-top: 75%;
}
.ratio-3-1::before {
padding-top: calc(100% / 3);
}
.ratio-2-1::before {
padding-top: 50%;
}<div class="wrapper"> <!-- Just to make things a bit smaller -->
<p>
Example of an 4:3 aspect ratio, filled by an image with an 1:1 ratio.
</p>
<div class="image-container ratio-4-3"> <!-- Lets go for a 4:3 aspect ratio -->
<img src="https://placekitten.com/1000/1000/" alt="Kittens!" />
</div>
<p>
Just place other block elements around it; it will work just fine.
</p>
</div>lets say you have 2 divs the outher div is a container and the inner could be any element that you need to keep its ratio (img or an youtube iframe or whatever )
html looks like this :
<div class='container'>
<div class='element'>
</div><!-- end of element -->
<div><!-- end of container -->
lets say you need to keep the ratio of the "element" ratio => 4 to 1 or 2 to 1 ...
css looks like this
.container{
position: relative;
height: 0
padding-bottom : 75% /* for 4 to 3 ratio */ 25% /* for 4 to 1 ratio ..*/
}
.element{
width : 100%;
height: 100%;
position: absolute;
top : 0 ;
bottom : 0 ;
background : red; /* just for illustration */
}
padding when specified in % it is calculated based on width not height. .. so basically you it doesn't matter what your width it height will always be calculated based of that . which will keep the ratio .
For me, this approach worked best, so I am sharing it with others so they can benefit from it as well.
.cont {
border: 5px solid blue;
position: relative;
width: 300px;
padding: 0;
margin: 5px;
resize: horizontal;
overflow: hidden;
}
.ratio {
width: 100%;
margin: 0;
display: block;
}
.content {
background-color: rgba(255, 0, 0, 0.5);
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
margin: 0;
}<div class="cont">
<canvas class="ratio" width="16" height="9"></canvas>
<div class="content">I am 16:9</div>
</div>.cont {
border: 5px solid blue;
position: relative;
height: 170px;
padding: 0;
margin: 5px;
resize: vertical;
overflow: hidden;
display: inline-block; /* so the div doesn't automatically expand to max width */
}
.ratio {
height: 100%;
margin: 0;
display: block;
}
.content {
background-color: rgba(255, 0, 0, 0.5);
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
margin: 0;
}<div class="cont">
<canvas class="ratio" width="16" height="9"></canvas>
<div class="content">I am 16:9</div>
</div>Just an idea or a hack.
div {
background-color: blue;
width: 10%;
transition: background-color 0.5s, width 0.5s;
font-size: 0;
}
div:hover {
width: 20%;
background-color: red;
}
img {
width: 100%;
height: auto;
visibility: hidden;
}<div>
<!-- use an image with target aspect ratio. sample is a square -->
<img src="http://i.imgur.com/9OPnZNk.png" />
</div>New in Chrome 88 and soon to follow in other browsers is the new CSS aspect-ratio property.
The aspect-ratio CSS property sets a preferred aspect ratio for the box, which will be used in the calculation of auto sizes and some other layout functions.
div {
background: rebeccapurple;
height:100px;
margin:1em auto;
}
.square {
aspect-ratio: 1 / 1;
}<div class="square">
</div>
CSS has a new property for this: aspect-ratio.
https://developer.mozilla.org/en-US/docs/Web/CSS/aspect-ratio
@supports (aspect-ratio: 1 / 1) {
div {
aspect-ratio: 16 / 9;
background-color: orange;
}
}<div style="width: 200px"></div>
<hr />
<div style="width: 400px"></div>
<hr />
<div style="height: 50px"></div>
<hr />
<div style="height: 10px"></div>Chrome and Edge have been supporting this fully since V88, and Firefox has been supporting it behind a flag since V81 (set layout.css.aspect-ratio.enabled to true in about:config).
For compatibility information, check https://caniuse.com/mdn-css_properties_aspect-ratio
aspect-ratio property) is not novel; the answer I linked to from 2020 also uses aspect-ratio. However, the answer I linked to also has little detail in terms of how it might be used, compared to this answer.
The new aspect-ratio tag would be awesome, but it messed up the positioning of my divs. The traditional solution of padding a wrapper div, works, but only adjusts the size according to the width of the parent or the viewport, which makes it problematic when the height is the limiting factor.
I found the min() function to be very useful, and adjusted the traditional method like so:
body{
background-image: linear-gradient(to top right, #FFE6B5, #B3CEBF);
padding: 0;
margin: 0 auto;
overflow-y: hidden; /* this is to avoid scrolling when the height of the viewport is less than what the aspect ratio requires */
}
.wrapper {
position: relative;
width: 100vw;
max-height: 100vh;
}
.sixteen-by-nine.aspect-ratio {
padding-bottom: 56.25% /* 9:16 ratio */
}
.content {
position: absolute;
top: 0; bottom: 0; left: 0; right: 0;
background-color: green
}
.centered {
position: absolute;
left: 50%;
top: 50%;
transform: translate(-50%, -50%);
height: 100%;
width: min(177.8vh, 100%); /* this always keeps a 16:9 ratio within the viewport */
font-size: min(3vh,1.7vw); /* if you are also interested in scaling the font size */
background-color: blue
}<body>
<div class="wrapper">
<div class="sixteen-by-nine aspect-ratio"></div>
<div class="content" >
<div class="centered">
<!-- stuff goes here -->
</div>
</div>
</div>
</body>Say that you like to maintain Width: 100px and the Height: 50px (i.e., 2:1) Just do this math:
.pb-2to1 {
padding-bottom: calc(50 / 100 * 100%); // i.e., 2:1
}
I just created a 2:1 div that resized to occupy the full width, but then shrinks the width if it would cause the top or bottom to exceed. But note, this will only work with the size of the window, not the size of the parent.
#scene {
position: relative;
top: 50vh;
left: 50vw;
width: 100vw;
height: 50vw;
max-height: 100vh;
max-width: calc(100vh * 2);
transform: translate(-50%, -50%);
}
I'm sure you can work out the correct %'s to use for 4:3 instead of 2:1.
I used a new solution.
.squares{
width: 30vw
height: 30vw
To main aspect ratio
.aspect-ratio
width: 10vw
height: 10vh
However, this is relative to the entire viewport. So, if you need a div that is 30% of the viewport width, you can use 30vw instead, and since you know the width, you reuse them in height using calc and vw unit.
Here is my solution for maintaining an 16:9 aspect ratio in portrait or landscape on a div with optional fixed margins.
It's a combination of width/height and max-width/max-height properties with vw units.
In this sample, 50px top and bottom margins are added on hover.
html {
height: 100%;
}
body {
margin: 0;
height: 100%;
}
.container {
display: flex;
justify-content: center;
align-items: center;
height: 100%;
}
.fixedRatio {
max-width: 100vw;
max-height: calc(9 / 16 * 100vw);
width: calc(16 / 9 * 100vh);
height: 100vh;
/* DEBUG */
display: flex;
justify-content: center;
align-items: center;
background-color: blue;
font-size: 2rem;
font-family: 'Arial';
color: white;
transition: width 0.5s ease-in-out, height 0.5s ease-in-out;
}
.fixedRatio:hover {
width: calc(16 / 9 * (100vh - 100px));
height: calc(100vh - 100px);
}<div class='container'>
<div class='fixedRatio'>
16:9
</div>
</div>I guess just using rem or em should solve the problem of fixed ratio but wont be hard bound to the screen as vw or vh or as painfull to use with flexbox as % is. Well, none of the answers worked properly for me, and in my case this attended me:
<div class="container">
<div>
</div>
</div>
.container {
height: 100vh;
width: 100vw;
}
.container div {
height: 4em;
width: 3em;
}
Or using rem. But anyway, any of them should make it.
rem uses the default font-size value as em use the closest font-size.
padding-bottom. Things changed andaspect-ratiois now the way to go. Ex.:aspect-ratio: 4 / 3;