Ruoyi-Flask-admin/app/static/jslib/jquery-easyui-1.3.4/themes/metro-orange/validatebox.css

.validatebox-invalid {
  background-image: url('images/validatebox_warning.png');
  background-repeat: no-repeat;
  background-position: right center;
  border-color: #ffa8a8;
  background-color: #fff3f3;
  color: #404040;
}