Open the page in firefox. However, first, download the firebug extension. Then, right click on the offending version and go down to inspect element.
Firebug is awesome because it let's you navigate the css of any element. You have two options here:
1) Assign the topmost element an css class and work it that way.
or
If that's not an option, you can use firebug to get the xpath to the offending element.
Xpaths look like body/table/tr/td/table/tr[2]
what you want to do with that in css is
body table tr td table tr {
/*css goes here */
}
Option 1 is definitely the better pick. Option 2 is more of a dirty way of getting things
done when things like asp.net doesn't let us have the fine grain of control we want.
It would be really awesome if you used a pastebin and posted the link to your rendered page's html.