discourse/app/assets/stylesheets/mobile/admin_reports.scss

.admin-reports {
  .admin-report {
    .body {
      flex-direction: column;

      .filters {
        order: 0;
        margin: 0;
        width: 100%;
      }

      .main {
        order: 2;
      }

      .report-alert {
        margin: 0;
        order: 1;
        flex: 1;
        padding: 1em;
      }
    }
  }
}