[Javascript] changing style sheet properties

[javascript@xxxxxxxxxx (Lau)]

I have a style sheet that I include in all my pages thus:

  <link REL=stylesheet HREF=default.css'>

it contains the following  style definition:

TD.LstVl{
 background:#FFFFE6;
 vertical-align:top;
 text-align:left;
 font:11px verdana;
 color:#000000;
}

Now for one particular page I want to change:
vertical-align:top;
to
vertical-align:middle;

I know that if I gave all my <TD>'s ID's then I could change them individualy using
mytdid.style.vertical-align=middle
but its impossible to do that as I'm generating my page using ASP and I won't know how many <TD>'s
there will be.

There are several long and complicated reasons why I don't want to add another definition to my
style sheet.

Thanks in advance for your help.

Lau