type="image/x-icon"什么意思啊,

我加了显示在tab中的icon,要是使用<link rel="shortcut icon" href="/favicon.ico" type="image/x-icon" />这条语句我界面中设置了position:absolute,z-index:1的那些图片和div全都向下移动了，不知道为什么，要是把type="image/x-icon"去掉，设置了position:absolute,z-index:1的那些图片和div都显示正常。
html中红色部分显示位置下移了又几百px:
<div id='product_pic' >
<div id='vconveter' style='float:left;padding:5px;width:302px;height:400px;position:relative'>
    <img width='302' height='400' src='/res/title.png' alt='product' class='home_pf_img' />
    <div class='home_pt_div'>FoxVideoConverter</div>
    <a href='/software/video/FoxConveter_info.php'><img  width='274px' height='251px' src='/res/FoxVideoConverter.png' alt='FoxVideoConverter'  class='home_pt_img'  /></a>
     <div style='z-index:2;position:absolute;top:310px;left:10px;width:280px;height:65px;text-align:center'>
     <p class='tenf'>Convert any video format to any one you want,like vcd,dvd,flv,mp4,3gp and so on.</p>
     <span style='display:inline-block;width:80px'><a class='nodecoration' href='/software/video/FoxConveter_info.php'>Trail</a></span>
     <span style='display:inline-block;width:80px;visibility:hidden'><a class='nodecoration' href='/register/fvc.php'>Buy</a></span>
     <span style='display:inline-block;width:110px'><a class='nodecoration' href='/software/video/FoxConveter_info.php'>Learn more>></a></span>
     </div>
</div>
</div>
下面是css:
.home_pf_img{
    z-index:1;
    position:absolute;
    top:0px;
    left:0px
}
.home_pt_div{
    z-index:2;
    position:absolute;
    top:10px;
    left:15px;
    width:274px;
    font-weight:bold;
    text-align:center
}
.home_pt_img{
    cursor:pointer;
    z-index:2;
    position:absolute;
    top:50px;
    left:15px;
    opacity:1.0;
    filter:alpha(opacity=100); /* For IE8 and earlier */
}
.home_pt_img:hover
{
    opacity:0.6;
    filter:alpha(opacity=60); /* For IE8 and earlier */
    .tenf{
    font-size:14px;
}