Facebook Comment Plugin override my header div when scrolling

Question

Yes, like in the title, the Facebook Comment Plugin override my header div when scrolling.

This is before scrolling:

This is after scrolling:

Style of header bar:

#header {
    height:45px;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    opacity: 0.95;
    background: #2D2D2D;
}
#colorbars {
    border-top: 3px solid #DD5044;
    height:42px;
    border-bottom: 8px solid rgba(40, 40, 40, .2);
}
#headercontainer {
    width: 940px;
    overflow: hidden;
    margin: 0 auto 0 auto;
}

HTML of header bar:

<div id="header"><header id="colorbars"><div id="headercontainer">
// content
</div></header></div>

And code of Facebook Plugin is:

<fb:comments href="<?php echo $facebook_href; ?>" width="655" num_posts="4"></fb:comments>

Answer 1

Does setting the z-index of the header help?

#header {
    /* ... */
    z-index: 9999;
}