discourse/plugins/chat/assets/stylesheets/mobile/chat-footer.scss

.full-page-chat {
  #main-chat-outlet.chat-view {
    grid-template-areas:
      "list"
      "footer";
  }

  .channels-list {
    grid-area: list;
    padding-bottom: 0;
  }

  .c-footer {
    grid-area: footer;
    background: var(--secondary);
    border-top: 1px solid var(--primary-low);
    display: flex;
    align-items: flex-end;
    justify-content: space-around;
    position: sticky;
    bottom: 0;
    left: 0;
    padding-bottom: env(safe-area-inset-bottom);

    &__item {
      display: flex;
      flex-direction: column;
      align-items: center;
      flex-basis: 33%;
      flex-shrink: 0;
      padding-block: 0.75rem;
      height: 100%;

      &.--active {
        .d-icon,
        .d-button-label {
          color: var(--quaternary);
        }
      }

      .d-icon {
        margin-right: 0;
        font-size: var(--font-up-4);
        color: var(--primary-medium);

        &.d-icon-discourse-threads {
          font-size: var(--font-up-3); //visual correction
        }
      }

      .d-button-label {
        font-size: var(--font-down-1-rem);
        color: var(--primary-medium);
      }
    }
  }
}

.has-full-page-chat div#reply-control {
  display: none;
}