The z-index CSS property specifies the z-order of an element and its descendants. When elements overlap, z-order determines which one covers the other. An element with a larger z-index generally covers an element with a lower one.
For a positioned box, the z-index property specifies:
1) The stack level of the box in the current stacking context.
2) Whether the box establishes a local stacking context.
<!DOCTYPE html> <html> <head> <style> h1 { position: absolute; left: 0px; top: 0px; z-index: -1; } </style> </head> <body> <h1 style="color:#FFCC99;">This is a heading</h1> <p> Because the h1 has a z-index of -1, it will be placed behind the text. </p> </body> </html>