@github/details-dialog-element/dist/index.css

A modal dialog opened with a <details> button.

/* This lives outside of element so it can work without JS */
details-dialog {
  position: fixed;
  margin: 10vh auto;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  z-index: 999;
  max-height: 80vh;
  max-width: 90vw;
  width: 448px;
  overflow: auto;
}