So my script works perfectly, but here is the issue, I have buttons (Sprite action here) that are 40px height, but the top 20 only shows perfectly. When you click the button ie img the bottom 20px show perfecto! but... Issue, i included in my script a way to return all others to there default (only one should be selected) now, how can I fix this issue that I seem unable to correct as I can select multiple of them ** USERS can switch ** The last part of the script that is the issue. Thanks

$(document).ready(function() {
    $('.form_sub').hide();
    $('.theader').addClass('active');

    $('.theader_t').click(function() {
        $('.form_header').show();
        $('.form_sub').hide();
        $('.theader').addClass('active');
        $('.sub_theader').removeClass('active');
    });
    $('.sub_theader_t').click(function() {
        $('.form_header').hide();
        $('.form_sub').show();
        $('.theader').removeClass('active');
        $('.sub_theader').addClass('active');
    });

    $('.top_head_img').click(function() {
        $(this).css({
            position: 'relative',
            bottom: '20px'
        }).siblings().css(
            'bottom', '0'
        );
    });
});

<ul class="top_head">
    <li>
    <a href="javascript:void(0)" onClick="selectPic5('top');"><img src="custom/images/top2.jpg" alt="Left" border="0" class="top_head_img"/></a>
    </li>
    <li>
    <a href="javascript:void(0)" onClick="selectPic5('center');"><img src="custom/images/mid2.jpg" alt="Center" border="0" class="top_head_img"/></a>
    </li>
    <li>
    <a href="javascript:void(0)" onClick="selectPic5('bottom');"><img src="custom/images/bot2.jpg" alt="Right" border="0" class="top_head_img"/></a>
    </li>
</ul>