CSS 不起作用,该怎么解决

if($auth==true){    echo "<tr>";    echo "<td class='block_link' id='block_link'><div style='width:100%; overflow:hidden; text-align:left; font-size:8.5pt;'>You have</div><div style='width:100%; overflow:hidden; text-align:right; font-size:27.5pt;'>\$$credit</div></td>";    echo "<td class='block_link'><a href='user_center.php'>Start Order</a></td>";    echo "<td class='block_link'><a href='user_center.php'>View Order</a></td>";    echo "<td class='block_link'><a href='user_cp.php'>Edit Profile</a></td>";    echo "<td class='block_link'><a href='user_cp.php'>Change Password</a></td>";    echo "<td class='block_link'><a href='recharge.php'>Recharge My Account</a></td>";    echo "<td class='block_link'><a href='logout.php'>Logout</a></td>";    echo "</tr>";}

.block_link a{    width:120px;    height:50px;    display: block;    background-color:#f1f1f1;    text-align:center;    font-size:10.5pt;    text_decoration:none; //去链接下划线不起作用    padding-top:30px;}.block_link a:link, block_link a:visited  //这里的a:visited 也不起作用{    background-color: #f1f1f1;    text_decoration:none; //去链接下划线不起作用    color:#009EDD;}.block_link a:hover{    background-color: #009EDD;    text_decoration:none; //去链接下划线不起作用    color:#ffffff;}#block_link{    background-color:#d34836;    color:#ffffff;    width:120px;}