Volume problem

When opened in firefox browser, the player volume doesn’t work properly. Clicking th ebutton auto mute and block volume slider against moving up…

Firefox shows, there is an error in below event:
<div class=”volume-slider-handle”></div>
<input type=”range” min=”0″ max=”1″ step=”0.05″ value=”0.8″>

It seems, it is related with this part of code:

function(e, n, t, r) {
var l = xu,
a = Fu.transition;
Fu.transition = null;
try {
xu = 1, de(e, n, t, r)
} finally {
xu = l, Fu.transition = a
}
}

I would appreciate the bug fix!
Thanks!

The page I need help with: [log in to see the link]