Every alternate thread background color is little deeper, how can i change that to more deeper?

 

custom.css .. .add ...

.ipsDataList.ipsDataList_zebra .ipsDataItem:nth-child(2n):not(.ipsDataItem_selected):not(.ipsModerated):not(.ipsDataItem_new):not(.ipsDataItem_success):not(.ipsDataItem_warning):not(.ipsDataItem_error):not(.ipsDataItem_info):not(.ipsDataItem_status) {
  color: #000;
}

obviously use your own color

NOTE: Doing this will also alter the color on the main forum page

looks alright as is.