How do they do this. position: scroll fixed?

On this page, how do they program the “social sharing” div (you’ll see it over on the left side), so that it scrolls until it reaches the top of the viewport, then its fixed until it reaches the footer?

Any ideas?

It’s done with JavaScript, but there are so many dang scripts on that page I can’t see which one it is. I’ll move this to the JS forum so someone with better eyes can help you.

It’s the code in the news.tron…post.compressed.js file, of which a part of the mootools code contains:

var ShareBar = new Class({
    Extends: Fixation,
    Implements: [Options, Events],
    options: {
        defaultView: "side",
        enableToggle: true,
        barId: "shareBar",
        views: {

If you’re more used to jQuery, there’s the floater plugin which does the job well too.

Thanks for the help guys. I was hoping they were somehow doing it with CSS3

Still holding out hope that Paul O might reach into his bag o tricks for an unscripted, CSS solution, but I kinda doubt there is one to be had.