Hide Price in email

Hi, i’m trying to remove the price column from the Order detail table (is the last column).
I thought that I can achieve the result by adding some custom css, something brutal like:
.woocommerce-Price-amount{display:none !important}

so I added the rule on Custom CSS section but doesn’t works at all.
Any clue?
I’ve tried also with something naif like:
*{color: red !important} but I can’t see any change.

thank you