height: calc(100%) not working correctly in CSS

Question

I have a div that I want to fill the whole height of the body less a set number in pixels. But I can't get height: calc(100% - 50px) to work.

The reason I want to do this is I have elements that have dynamic heights based on some varying criteria, e.g. height of the header changes based on different elements it can contain. A content div then needs to stretch to fill the rest of the available space available.

The div element, however, stays the height of the content - it doesn't seem as if it interprets 100% to be the height of the body element.

body {    background: blue;    height: 100%;  }    header {    background: red;    height: 20px;    width: 100%;  }    h1 {    font-size: 1.2em;    margin: 0;    padding: 0;    height: 30px;    font-weight: bold;    background: yellow;  }    #theCalcDiv {    background: green;    height: calc(100% - (20px + 30px));    display: block;  }

<header>Some nav stuff here</header>  <h1>This is the heading</h1>  <div id="theCalcDiv">This blocks needs to have a CSS calc() height of 100% - the height of the other elements.</div>

I would appreciate any help or pointers in the right direction.

Answer 1

First off - check with Firebug(or what ever your preference is) whether the css property is being interpreted by the browser. Sometimes the tool used will give you the problem right there, so no more hunting.

Second off - check compatibility: http://caniuse.com/#feat=calc

And third - I ran into some problems a few hours ago and just resolved it. It's the smallest thing but it kept me busy for 30 minutes.

Here's how my CSS looked

#someElement {     height:calc(100%-100px);     height:-moz-calc(100%-100px);     height:-webkit-calc(100%-100px); } 

Looks right doesn't it? WRONG Here's how it should look:

#someElement {     height:calc(100% - 100px);     height:-moz-calc(100% - 100px);     height:-webkit-calc(100% - 100px); } 

Looks the same right?

Notice the spaces!!! Checked android browser, Firefox for android, Chrome for android, Chrome and Firefox for Windows and Internet Explorer 11. All of them ignored the CSS if there were no spaces.

Hope this helps someone.

Answer 2

You need to ensure the html and body are set to 100% and also be sure to add vendor prefixes for calc, so -moz-calc, -webkit-calc.

Following CSS works:

html,body {     background: blue;     height:100%;     padding:0;     margin:0; } header {     background: red;     height: 20px;     width:100% } h1 {     font-size:1.2em;     margin:0;     padding:0;     height: 30px;     font-weight: bold;     background:yellow } #theCalcDiv {     background:green;     height: -moz-calc(100% - (20px + 30px));     height: -webkit-calc(100% - (20px + 30px));     height: calc(100% - (20px + 30px));     display:block } 

I also set your margin/padding to 0 on html and body, otherwise there would be a scrollbar when this is added on.

Here's an updated fiddle

http://jsfiddle.net/UF3mb/10/

Browser support is: IE9+, Firefox 16+ and with vendor prefix Firefox 4+, Chrome 19+, Safari 6+