Things to notice about this box:

• It uses rounded corners, gradients, borders and an image background.
• The gradient is scaled to the heading, but bleeds through to the main text.
• The text box is partially transparent.
• Text can appear with the rounded corners.
• There's even a box shadow.
• The effect uses no javascript, nor any images.
• In short, this is how the web should be.
• However, the aliasing on the corners is phenomenally ugly.