discourse/plugins/chat/assets/stylesheets/common/chat-user-avatar.scss

.chat-user-avatar {
  @include unselectable;
  display: flex;
  align-items: center;

  &.is-online {
    .avatar {
      padding: 2px;
      box-shadow: inset 0px 0px 0px 1px var(--success),
        inset 0px 0px 0px 2px var(--secondary);
    }
  }

  &__container {
    .chat-user-presence-flair {
      box-sizing: border-box;
      position: absolute;
      background-color: var(--success);
      border: 1px solid var(--secondary);
      border-radius: 50%;

      .chat-message & {
        width: 10px;
        height: 10px;
        right: 0px;
        bottom: 0px;
      }

      .chat-channel-title & {
        width: 8px;
        height: 8px;
        right: -1px;
        bottom: -1px;
      }
    }
  }

  .chat-message-container:not(.has-reply) & {
    width: var(--message-left-width);
    flex-shrink: 0;
  }

  .chat-channel-title & {
    width: auto;
  }
}