Header message just like at Stack Overflow

Question

This is the first time I visited stack overflow and I saw a beautiful header message which displays a text and a close button.

The header bar is fixed one and is gre

Answer 1

The relevant css would include:

position: fixed;
top: 0;
width: 100%;

More information about position:fixed:

An element with position: fixed is positioned at the specified coordinates relative to the browser window. The element's position is specified with the "left", "top", "right", and "bottom" properties. The element remains at that position regardless of scrolling. Works in IE7 (strict mode)

If IE6 support is important to you, you may wish to research workarounds.