<!DOCTYPE html> <html> <head> <style type="text/css" media="screen"> .box { position: relative; height: 100px; width: 100px; margin: 10px; background-color: blue; } .slow { -webkit-animation: slow 2s infinite linear alternate; } .fast { -webkit-animation: fast 2s infinite linear alternate; } @-webkit-keyframes slow { from { left: 0px; } to { left: 400px; } } @-webkit-keyframes fast { from { -webkit-transform: translateX(0); } to { -webkit-transform: translateX(400px); } } </style> </head> <body> <p>The lower box should animate more smoothly than the upper one (on Mac).</p> <div class="box slow"></div> <div class="box fast"></div> </body> </html>