Question about table style that is inside another table


So, I was having some issues with firefox and IE not showing the correct border size/color, although they were working on Chrome. So I used this css table style and now they show up fine:

table,td,th {border:1px solid #171717;}

Now the issue is this: This table is inside another table, let’s call it main.
I do not want to apply that css on the main table.
Is that possible? :sigh:

To sum up, I have a table that I want to style, which is inside another table that I don’t want to use style(border in particular).
I tried classes but it didn’t work.