Set div height equal to screen size

Using CSS {height: 100%;} matches the height of the parent. This could be anything, meaning smaller or bigger than the screen. Using {height: 100vh;} matches the height of the viewport.

.container {
    height: 100vh;
    overflow: auto;
}

According to Mozilla's official documents, 1vh is:

Equal to 1% of the height of the viewport's initial containing block.

You need to give height for the parent element too! Check out this fiddle.

CSS:

html, body {height: 100%;}

#content, .container-fluid, .span9
{
    border: 1px solid #000;
    overflow-y:auto;
    height:100%;
}​

JavaScript (using jQuery) Way:

$(document).ready(function(){
    $(window).resize(function(){
        $(".fullheight").height($(document).height());
    });
});

try this

$(document).ready(function(){
    $('#content').height($(window).height());
});