FBML request-form display problem.

Question

I have a request-form tag with a request-form-submit button. Problem is: when I click on the submit button, the popup form appears on top of the button, and it is not in the center of the window. See image:

See image here: http://i46.tinypic.com/25yzzfk.png

It is also hidden by other images. Anybody knows how I can get the popup to be displayed in the center of the window and on top of the other elements?

Thanks.

<span class="send_friend_btn">
                       <fb:serverfbml style="height: 10px;">
                            <script type="text/fbml">
                                    <fb:fbml>                                        
                                    <fb:request-form action="<?php echo url_for(sfConfig::get('app_fb_baseurl').'gift/showVisit');?>"
                                    method="get"
                                    content="<?php echo $username;?> has sent you a <?php echo $gifts->getName() ?> in World.<br /><br />"
                                    type="Gift"
                                    invite="false"
                                    target="_top"
                                    style="text-align: center; height: 25px; width: auto; position:fixed; top:30px; right:5px; background-color: #bfe2f6 ">
                                    <input type="hidden" name='gift_id' value="<?php echo $gifts->getId();?>" fb_protected="true" />
                                    <input type="hidden" name='sentfrom_id' value="<?php echo $uid;?>" fb_protected="true" />
                                    <input type="hidden" name='friend_id' value="123456789123" fb_protected="true" />
                                    <input type="hidden" name='fromuserid' value="<?php echo $uid; ?>" fb_protected="true" />
                                    <input type="hidden" name='gifticon' value="<?php echo $gifts->getIcon();?>" fb_protected="true" />
                                     <fb:request-form-submit uid="123456789123" label="Send to %n" />
                                    </fb:request-form>
                                    </fb:fbml>                                        
                            </script>
                        </fb:serverfbml>
                        </span>

My CSS:

.send_friend_btn {
padding-top: 0px;
height: 25px; /*25px*/
width: 100%;
overflow:hidden;
z-index: 100;

}