How can I make a div 100% of window height?

20
votes

I just want to have a sidebar that will be 100% of window height, but nothing works except this:

#sidebarBack {
background: rgba(20, 20, 20, .3);
position: fixed;
width: 250px;
height: 100%;
left: 0;
}

I don't want to have position: fixed, because I have horizontally scrollable content, so a fixed part would remain, well, fixed.

Is there any way to do such a thing, maybe with relative or absolute position?

Here's an quick Fiddle just for a test and explanation: JSFiddle

5
htmlcss
Forgive me, but I'm a little curious - If you are able to scroll it, doesn't that defeat the idea of making it the height of the page? - George
Do you want the sidebar to scroll out of the window, or stay where it is? And hide the scrollable code under the sidebar? - EricG
I want it to scroll out of the window if content is being scrolled. Like a relative/absolute position... Just like Wordpress admin panel... They have something similar... - dvlden

5 Answers

44
votes

You can use the new and so-useful-I-can't-imagine-what-took-W3C-so-long vh CSS unit:

height:100vh;
36
votes

tl;dr - add html, body {height:100%;} to your CSS.

Percentage values in CSS are inherited from some ancestor that already has height declared. In your case, you need to tell all parents of your sidebar to be 100% height. I'm assuming that #sidebarBack is a direct child of body.

Essentially, your code above is telling #sidebarBack to be 100% height of its parent. Its parent (we are assuming) is body, so you need to set height: 100%; on body as well. We can't stop there, however; body inherits height from html, so we also need to set height: 100%; on html. We can stop here, because html inherits its properties from viewport, which already has a declared height of 100%.

This also means if you end up putting the #sidebar inside another div, then that div also needs height:100%;.

Here is an Updated JSFiddle.

Changed your CSS to:

html, body {
    height:100%;
}

#sidebar {
    background: rgba(20, 20, 20, .3);
    width: 100px;
    height: 100%;
    left: 0;
    float:left;
}

section#settings {
    width:80%;   
    float:left;
    margin-left:100px;
    position:fixed;
}
7
votes

First, tell the body element to fill the window, rather than shrinking to the size of the content:

body { position: absolute; min-height: 100%; }

by using min-height instead of height, body will be allowed to expand beyond the window's height when the content is longer than the window (i.e. this allows for vertical scrolling when needed).

Now, set your "#sidebar" to be position:absolute, and use top:0; bottom:0; to force it to fill the parent element's vertical space:

#sidebar {
    position: absolute;
    top:0; bottom:0;
    left: 0;
    width: 100px;
    background: rgba(20, 20, 20, .3);
}

Here are a couple of jsFiddles:

As you'll see, in both examples, I've preserved your width setting on the "#settings" section, thus showing that horizontal scrolling works as you requested.

1
votes

Try the following

#sidebarBack {
 background: rgba(20, 20, 20, .3);
 position: fixed;
 width: 250px;
 top:0;
 bottom:0;
 left: 0;
}
0
votes

Try this - 

html,body{height:100%;}
#sidebar {
background: rgba(20, 20, 20, .3);
/*position: fixed;*/
width: 100px;
height: 100%;
left: 0;
float:left;
}


section#settings {
width: 62%;
height: auto;
display: inline-block;
position: relative;
margin-left: 100px;
float:left;
}

​