I have done this to myself many times. Have you ever thought, I want all my tables to look like XYZ. So you throw table { border-color: blue; … } into CSS.
The problem is now you are stuck with that for all tables. I think you should have a table style like table.blue_border { border-color: blue; …} that you can now apply to only the tables you want to with <table class=’blue_border’>.
You will inevitably need a standard table somewhere without the same style as the rest, but now you have to do more work to make that happen. Do yourself a favor, use a reset for all HTML elements, and don’t style them directly. Style a class that you will put on those elements.