Safari OSX : Demo page glitch

[curtisk]

When visiting the demo page http://labs.mintchaos.com/flippant.js/ using Safari Version 6.0.5 (8536.30.1) on OSX 10.8.4 if you open any of the modal windows and leave them open long enough for the "js" flip in your page header

<h1>
Flippant.
<span>js</span>
</h1>

The "Modal >>" and "Card >>" buttons on one of the other demo blocks will flash rapidly as the "js" spins, appearing like they pop through the flippant-modal-dark div