Each table would have it’s own “ID”. It will show in the them a class=IDHERE
The same ID will show in the .css file, your style sheet. By editing the colours, fonts etc here, tables with that class will use the new style.
Things like the main page background will be high up in the .css list.
By Googling css or html for dummies, I’m sure there will be some good guides to help you.
Hope this helps!