BuddyPress.org

Hi,
Please help.
On Activity/wall, I would like to have the background color of all original posts white and then all comments/replies background color to be grey.

I tried using this CSS code, but the background colors for comments/replies only change after I do a level 2 reply. Then if I refresh the page, they all go back to white, until I add another level 2 comment. Any ideas to try? Thanks

#buddypress ul.item-list li {
background-color: white;
margin-bottom: 20px;
}

/* Level 1 comment */
#buddypress div.activity-comments ul.has-comments li {
    background: grey;
}

/* Level 2 reply comment */
#buddypress div.activity-comments ul.has-comments li ul li{
    background: grey !important;
}

/* Level 3 reply comment */
#buddypress div.activity-comments ul.has-comments li ul li ul li{
    background: grey !important;
}