@exadel/esl/modules/esl-panel/core.css

Exadel Smart Library (ESL) is the lightweight custom elements library that provide a set of super-flexible components

esl-panel {
  display: block;
  height: auto;
  overflow: hidden;
  visibility: hidden;
  max-height: 0;
  transition: max-height 0.5s ease-in-out, visibility 0s linear 0.5s;
}
esl-panel.open {
  visibility: visible;
  max-height: none;
  transition: max-height 0.5s ease-in-out, visibility 0s linear;
}
@media print {
  esl-panel:not(.print-closed) {
    visibility: visible;
    max-height: none;
  }
}