Floating Content stack
With the Floating Content stack you can easily make special content float on top of your normal page content. Simply set the margins from the top and side and this stack makes sure that the Floating Content position is automatically adjusted while scrolling the page or resizing the browser window.
Besides that it comes with a Responsive approach (based on CSS3 @Media that is supported by modern browsers). Meaning that you can automatically hide the Floating Content on smaller screens.