Shorthand notation of declaring top, right, bottom, left position

.element {
  inset: 1em 2em 3em 0; /* top right bottom left */
  inset: 10% 5% -10%;   /* top left/right bottom */
  inset: 0 10px;        /* top/bottom left/right */
  inset: 20px;          /* all edges = 20px */
}