userstyles/src/tildes-baukula/_topic-listing.scss

.topic-listing {
  // Make all the topics in the listing have the same background color
  > li:nth-of-type(n) {
    background-color: $background;
  }
}

// "Post" listing is the list on user profiles
.post-listing {
  .topic {
    background-color: $background;
  }
}