Set div to remaining height using CSS with unknown height divs above and below

2014 UPDATE: The modern way to solve this layout problem is to use the flexbox CSS model. It's supported by all major browsers and IE11+.


2012: The correct way to do this with CSS alone is to use display: table and display: table-row. These are supported by all major browsers, starting with IE8. This is not using tables for display. You'll use divs:

html, body {
    height: 100%;
    margin: 0;
}
.wrapper {
    display: table;
    height: 100%;
    width: 100%;
    background: yellow;  /* just to make sure nothing bleeds */
}
.header {
    display: table-row;
    background: gray;
}
.content {
    display: table-row;  /* height is dynamic, and will expand... */
    height: 100%;        /* ...as content is added (won't scroll) */
    background: turquoise;
}
.footer {
    display: table-row;
    background: lightgray;
}
<div class="wrapper">
    <div class="header">
        <h1>Header</h1>
        <p>Header of variable height</p>
    </div>
    <div class="content">
        <h2>Content that expands in height dynamically to adjust for new content</h2>
        Content height will initially be the remaining
        height in its container (<code>.wrapper</code>).
        <!-- p style="font-size: 4000%">Tall content</p -->
    </div>
    <div class="footer">
        <h3>Sticky footer</h3>
        <p>Footer of variable height</p>
    </div>
</div>

That's it. The divs are wrapped as you'd expect.


A cross-browser solution derived from Dan Dascalescu answer:

http://jsfiddle.net/Uc9E2

html, body {
    margin: 0;
    padding: 0;
    height: 100%;
}
.l-fit-height {
    display: table;
    height: 100%;
}
.l-fit-height-row {
    display: table-row;
    height: 1px;
}
.l-fit-height-row-content {
    /* Firefox requires this */
    display: table-cell;
}
.l-fit-height-row-expanded {
    height: 100%;
    display: table-row;
}
.l-fit-height-row-expanded > .l-fit-height-row-content {
    height: 100%;
    width: 100%;
}
@-moz-document url-prefix() {
    .l-scroll {
        /* Firefox requires this to do the absolute positioning correctly */
        display: inline-block;
    }
}
.l-scroll {
    overflow-y: auto;
    position: relative;
    height: 1000px;
}
.l-scroll-content {
    position: absolute;
    top: 0;
    bottom: 0;
    height: 1000px;
    min-height:100px;
}
<div class="l-fit-height">
    <section class="l-fit-height-row">
        <div class="l-fit-height-row-content">
            <p>Header</p>
        </div>
    </section>
    <section class="l-fit-height-row-expanded">
        <div class="l-fit-height-row-content l-scroll">
            <div class="l-scroll-content">
                <p>Foo</p>
            </div>
        </div>
    </section>
    <section class="l-fit-height-row">
        <div class="l-fit-height-row-content">
            <p>Footer</p>
        </div>
    </section>
</div>