gab-social/app/javascript/gabsocial/components/modal/compose_modal/compose_modal.scss

.compose-modal {
  width: 600px;

  &__content {
    .timeline-compose-block {
      background: transparent !important;
      width: 100%;
      padding: 10px 5px;
      margin-bottom: 0;

      .compose-form {
        display: flex;
        flex-direction: column;
        max-height: 100%;
      }
    }
  }
}