in (node_list.css)
.nodeList .categoryForumNodeInfo,
.nodeList .forumNodeInfo,
.nodeList .pageNodeInfo,
.nodeList .linkNodeInfo
{
@property "primaryContent";
background-color: @contentBackground;
padding: 10px;
border-bottom: 1px solid @primaryLighterStill;
@property "/primaryContent";
padding: 0;
}
or add the following in extra.css
.nodeList .categoryForumNodeInfo,
.nodeList .forumNodeInfo,
.nodeList .pageNodeInfo,
.nodeList .linkNodeInfo
{
background-color: white !important;
}