สอบถามหน่อยครับ ใช้ Google Chrome แล้วเห็นเส้นลิงค์เล็กๆ แต่ใช้ IE กับ Firefox กลับไม่เห็นเป็นเพราะอะไรครับ

<td style="background-repeat:no-repeat; background-position:center; background-repeat:inherit;" >
    <div style="float: left; width:500px;">
      <ul style="float: left;padding-left:30px; padding-top:10px; font-size:12px; color:#000; list-style:none;">
       <li style="list-style:none; color: #000;">
        <a href="index.php?p=home"><img src="/bt/home_01.png" 
          onmouseover="this.src='/bt/home01_click.png'" onmouseout="this.src='/bt/home_01.png'" border="0" />
        </a>
		 <br/>HOME
	   </li>
      </ul> 

	  <ul style="float: left; padding-left:25px; padding-top:10px; font-size:12px; color:#000; list-style:none; text-align: center;">
       <li style="list-style:none; color: #000;">
        <a href="index.php?p=about"><img src="/bt/about_02.png" 
         onmouseover="this.src='/bt/about_click.png'" onmouseout="this.src='/bt/about_02.png'" border="0" />
        </a>
		 <br/>ABOUT US
	   </li>
      </ul>  

	  <ul style="float: left; padding-left:20px; padding-top:10px; font-size:12px; color:#000; list-style:none; text-align: center;">
       <li style="list-style:none; color: #000;">
        <a href="index.php?p=gallery"><img src="/bt/Gallery_02.png" 
         onmouseover="this.src='/bt/gallery_click.png'" onmouseout="this.src='/bt/Gallery_02.png'" border="0" />
        </a>
		<br/> 
		GALLERY
	   </li> 
      </ul>
              
      <ul style="float: left; padding-left:17px; padding-top:10px; font-size:12px; color:#000; list-style:none; text-align: center;">
       <li style="list-style:none; color: #000;">
        <a href="http://www.mo-indi.com" target="_blank"><img src="/bt/download_03.png" 
         onmouseover="this.src='/bt/download_click.png'" onmouseout="this.src='/bt/download_03.png'" border="0" />
        </a>
	    <br/>DOWNLOAD
	   </li> 
      </ul> 

	  <ul style="float: left; padding-left:8px; padding-top:10px; font-size:12px; color:#000; list-style:none; text-align: center;">
       <li style="list-style:none; color: #000;">
        <a href="index.php?p=contact"><img src="/bt/contact_02.png" 
         onmouseover="this.src='/bt/contact_click.png'" onmouseout="this.src='/bt/contact_02.png'" border="0" />
        </a>
        <br/>CONTACT US
       </li>   
      </ul> 
     </div>
    </td>