Sorry, Your question wasn't clear. You reference you styles for the table just like you would any other element. There isn't anything special about them. To define styles for your table without using classes or id's you can do:
Let me share some rules in order to help you understand use of tables in CSS so that you can develop a better website design:
1. Tables love space. Set the width of tables carefully, according to the content. If you don’t know the perfect width, simply set the width of the table to 100%. Tables look nicer when they have “overwidth”, and when it comes to tables too much width is definitely better than too little width.
2. Cells need some padding. Sure, each table cell relates to each other. But it doesn’t mean that we have to pull them too close, right? Define some space between the cells, crammed up table cells are so much harder to read.
3. Treat tables the way you treat content. Tables are read similarly to the way we read text — except it’s harder and it takes more time to read a table. So be careful with the amount of contrast you are giving to your table. Use soft colors — it’s easier for the eyes. Don’t treat your table like it’s a graphical decoration. Make sure that the style you apply to it makes the content more readable, not the other way around.