Table styling issue

Hi, I love the way this site has turned out but there's one piece I haven't been able to resolve. I'm not sure if this is more theme or WooCommerce related but I'm hoping you will help. An example of this can be seen at https://tractorcats.com/product/tractor-cats-2025-12-month-wall-calendars-11x8-5-in-14x11-5-in/ I have been unable to change the color of the text in the size table seen on many of the products to white so it is all easily seen. It is not working, but I've left:

woocommerce-Tabs-panel table #size-guide thead th, table #size-guide tbody td {
color: #ffffff !important;
}

in place. Can you tell me what I am missing? Thank you