That's one of mine older issues which I was facing few months ago and today, while I was browsing through my pending blog posts, I decided to post few words about it hoping that it will save you few minutes of work if you ran into the same problem as I was.

So, let's imagine that you want to put some link (anchor tag) inside a div tag which has some image as a background and that your link need to positioned somewhere inside of the image (div's background). Your HTML code will then be something like this:

<div class="divsCSSClass">
    <a href="Default.aspx" style="left: 133px; position:relative; top: 7px;">
            some_text
     </a>
</div>

and your CSS will then be something like this:

.divsCSSClass {
     background: url('image_name.png');
     width:392px;
     height:45px;
}

Above code will work in IE and Opera, but in Firefox and Safari link (anchor) will not be clickable. The solution is extremely simple. All you need to do is to add position:relative; to div's CSS class. CSS will then be something like this:

 .divsCSSClass {
     background: url('image_name.png');
     width:392px;
     height:45px;
     position: relative;
}