<!DOCTYPE html> <html> <body> <style> #a { border: 1px solid black; width: 100px; height: 100px; left: 10px; } #b { border: 1px solid blue; width: 50px; height: 50px; left: 20px; } div { position: absolute; } </style> <div id="a"> <div id="b"> </div> </div> </body> </html>