使用max-width时会出现小点

Question

I want to get rid off small dots that appear when I use max-width (see // for details).

Here's my php that shows a messeage saved in session:

<?php
    echo "<table id='delpos'>";
    echo "<td id='del'>" . $_SESSION["del"] ."</td> "; 
    echo "</table>"; 
?>  

And css that doesn't show background-color (until session exists) by using max-width + max-height :

<style>
    #del {
        background-color:red ;
        color:white;
        max-width:20px;
        max-height:6px;
        overflow:hidden; // tried using this to hide the small "red" dots... 
    }

    #delpos {
        margin-top:60px;
        margin-left:30px;
        position:absolute;
    }
</style>

Please help:)