This is a Rounded Rectangle Box with drop down shadow that stretches or compresses according to its contents.
The images have been designed in Photoshop, and saved as GIFs (to allow for transparency).

top left (fixed)	top (var. width)	top right (fixed)
left (var. height)	You contents fits here.	right (var. height)
bottom left (fixed)	bottom (var. width)	bottom right (fixed)

Contrary to the rounded boxes provided with some toolboxes, this works on ALL browsers.
Resize your browser window to any width to try it!