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@intodesign, you can use percentages. The only thing your missing is setting html to height: 100% as well as the body.
With no height value provided for the HTML element, setting the height and/or min-height of the body element to 100% results in no height (before you add content).
4 Answers. Show activity on this post. height: 100% gives the element 100% height of its parent container. height: auto means the element height will depend upon the height of its children.
Height % is based on it's parent (so you have to set every element above the target element to 100%) , there are a few workarounds to this though. For instance you can set it to height: 100vh; This will create the element to be 100% of your window height. Or you can use px instead.
I am trying to set a div to a certain percentage height in CSS
Percentage of what?
To set a percentage height, its parent element(*) must have an explicit height. This is fairly self-evident, in that if you leave height as auto, the block will take the height of its content... but if the content itself has a height expressed in terms of percentage of the parent you've made yourself a little Catch 22. The browser gives up and just uses the content height.
So the parent of the div must have an explicit height property. Whilst that height can also be a percentage if you want, that just moves the problem up to the next level.
If you want to make the div height a percentage of the viewport height, every ancestor of the div, including <html> and <body>, have to have height: 100%, so there is a chain of explicit percentage heights down to the div.
(*: or, if the div is positioned, the ‘containing block’, which is the nearest ancestor to also be positioned.)
Alternatively, all modern browsers and IE>=9 support new CSS units relative to viewport height (vh) and viewport width (vw):
div {
height:100vh;
}
See here for more info.
You need to set the height on the <html> and <body> elements as well; otherwise, they will only be large enough to fit the content. For example:
<!DOCTYPE html>
<title>Example of 100% width and height</title>
<style>
html, body { height: 100%; margin: 0; }
div { height: 100%; width: 100%; background: red; }
</style>
<div></div>bobince's answer will let you know in which cases "height: XX%;" will or won't work.
If you want to create an element with a set ratio (height: % of it's own width), use the aspect-ratio property. Make sure height is not explicitly set on the element for it to work. https://developer.mozilla.org/en-US/docs/Web/CSS/aspect-ratio
.square {
width: 100%;
height: unset;
aspect-ratio: 1 / 1;
}
Historically, the best way to do this was to set the height using padding-bottom. Example for square:
<div class="square-container">
<div class="square-content">
<!-- put your content in here -->
</div>
</div>
.square-container { /* any display: block; element */
position: relative;
height: 0;
padding-bottom: 100%; /* of parent width */
}
.square-content {
position: absolute;
left: 0;
top: 0;
height: 100%;
width: 100%;
}
The square container will just be made of padding, and the content will expand to fill the container. Long article from 2009 on this subject: http://alistapart.com/article/creating-intrinsic-ratios-for-video
You can use 100vw / 100vh. CSS3 gives us viewport-relative units. 100vw means 100% of the viewport width. 100vh; 100% of the height.
<div style="display:flex; justify-content: space-between;background-color: lightyellow; width:100%; height:85vh">
<div style="width:70%; height: 100%; border: 2px dashed red"></div>
<div style="width:30%; height: 100%; border: 2px dashed red"></div>
</div>
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