Drop down menu is not working in Chrome or Firefox?

If the dropdown menu is not working in the Chrome or Firefox explorer then fix that with the help of this:

Fix the Dropdown menu without adding z-index to the head div.

#head {
    position:relative;
    height: 140px;
    width: 100%;
    background: #FFF;
    filter:alpha(opacity=93);
    padding-top:20px;
    /* CSS3 standard */
    opacity:0.93;
    -moz-box-shadow: 0 0 5px black;
    -webkit-box-shadow: 0 0 5px black;
    box-shadow: 0 0 5px black;
}

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