background color for div area

Hi,

I’m fairly new here, and have searched and tried for a couple of hours on this…

I’m trying to change the ‘shop’ page to completely white:

http://rickcassettari.com/shop/

I put this in my child theme css:

div#main {background-color: #FFFFFF;}

…and it succeeds in changing the home page main area to white. Though when I enter .page-id-190 div#main {background-color: #FFFFFF;}
(to only change the ‘shop’ page), it has no effect on the shop page, the main area remains black.

Any ideas on why the page id function is not working? I’m new at CSS, so anything would be helpful.

Thanks.