How to change the table background color

I think this is what you are looking for:

table, tr, td {
	background-color: transparent;
}

If you need other background to change, please be more specific.

Hi Florian,
Yes, thanks that was what I was looking for.
I have placed that pice of code in the custom-stule.css in the _custom folder and it works.
I did find that I have to disable the aggregate css function for the customized settings to work.

When you modify some CSS you have to disable the aggregate css function. After you are happy with the results, clear the cache and re-aggregate CSS.