Fixed positioning/z-index issue in mobile safari

Question

So the site in question: http://kaye.at/baby

The main content below scrolls up over the top of the countdown and under the navigation which are both fixed elements. This works fine on desktop but on mobile safari, the content scrolls behind the countdown as the user moves up but once touch is released, it pops in front.

Just wondering whether this is a bug or it is something that can be fixed?

Here's the CSS:

#header { position: fixed; width: 100%; top: 0px; z-index: 10; }
#content { width: 100%; position: relative; top: 650px; z-index: 7; }
#banner { position: fixed; width: 100%; position: fixed; background: url('http://kaye.at/baby/img/stork.jpg') no-repeat center bottom #fff;  padding-top: 185px; z-index: 1; }
#defaultCountdown { max-width: 70%; height: auto; }

And HTML (main structure):

<div id="header">
    <div id="nav">
        <ul>
            <li><a class="active" href="index.php">START</a></li>
            <li><a href="ultrasound-images.php">ULTRASOUND PICS</a></li>
            <li><a href="pinkorblue.php">PINK OR BLUE?</a></li>
        </ul>
    </div>
</div>

<div id="banner">
   <div id="defaultCountdown"></div>
</div>

<div id="content">
</div>

Answer 1

Ugh amazing. Just had to add:

-webkit-transform: translate3d(0,0,0);

to the #content div.