Make right panel a dark-panel instead of every descendant.

Also move bg color central.

res/css/views/rooms/_MemberInfo.scss

@@ -15,7 +15,6 @@ limitations under the License.
 */
 
 .mx_MemberInfo {
-    background-color: $secondary-accent-color;
     display: flex;
     flex-direction: column;
     flex: 1;

res/css/views/rooms/_MemberList.scss

@@ -17,7 +17,6 @@ limitations under the License.
 .mx_MemberList,
 .mx_GroupMemberList,
 .mx_GroupRoomList {
-    background-color: $secondary-accent-color;
     flex: 1;
     display: flex;
     flex-direction: column;

res/css/views/rooms/_RoomList.scss

@@ -37,7 +37,6 @@ limitations under the License.
 }
 
 .mx_RoomList_emptySubListTip_container {
-    background-color: $secondary-accent-color;
     padding-left: 18px;
     padding-right: 18px;
     padding-top: 8px;

res/css/views/rooms/_RoomTile.scss

@@ -23,7 +23,6 @@ limitations under the License.
     margin: 0;
     padding: 2px 12px;
     position: relative;
-    background-color: $secondary-accent-color;
 }
 
 .mx_RoomTile_tooltip {