lockfixed is a jQuery plugin which allows for DOM elements to be positioned anywhere on the page, and lock within the user's viewport when scrolling. Common use case is a menu under a header, which on scrolling stays within the viewport and doesn't overflow the footer.

Degrades nicely on mobile and tablet browsers and doesn't have any CSS prerequisites.

$.lockfixed(".menu");

or

$.lockfixed(".menu",{offset: {top: 10, bottom: 100}});

See demo.

Find the documentation.

Just send either one of us a message on Twitter: @yvoschaap.

lockfixed is released under the MIT license. See the license for details.