peertube-plugin-livechat/conversejs/custom/sass/_peertubetheme.scss

#conversejs.theme-peertube {
  // hidding avatars when screen width is not big enough.
  @media screen and (max-width: 576px) {
    .message {
      &.chat-msg {
        .chat-msg__content {
          width: 100%;
        }

        &.chat-msg--followup {
          &.chat-msg--with-avatar .chat-msg__content {
            margin-left: 0.5em;
          }
        }

        .chat-msg__avatar {
          display: none;
        }
      }
    }
  }

  // Bigger occupants sidebar when width is not big enough.
  @media screen and (max-width: 576px) {
    .chatroom {
      .box-flyout {
        .chatroom-body {
          .occupants {
            min-width: 50%;
          }
        }
      }
    }
  }
}