Not just your Mac - my Firefox & Chrome on Linux. Seems the color palettes in http://80legs.com/_images/bg-home.jpg vs http://80legs.com/_images/the-most-powerful-web-crawler-ever... don't match up. Looks great on all browsers on Windows, so I'm guessing the jpgs have a color profile attached.

Looks like http://80legs.com/_images/the-most-powerful-web-crawler-ever... uses slightly different gradient stops than http://80legs.com/_images/bg-home.jpg