discourse/plugins/chat/assets/stylesheets/desktop/chat-channel-title.scss

.chat-channel-title-wrapper {
  padding: 0.25rem;

  &:hover {
    background: var(--primary-very-low);
    border-radius: var(--d-border-radius);
  }

  .chat-channel-title {
    &__user-info {
      overflow: hidden;
    }
  }
}