/* letter dates */
.related-letters th:nth-of-type(1),
.related-letters td:nth-of-type(1) {
  width: calc(100% / 3);
}
/* letter description */
.related-letters th:nth-of-type(2),
.related-letters td:nth-of-type(2) {
  width: calc(100% / 3 * 2);
}

/* --- media queries --- */
@media (min-width: 40em) {
  /* letter dates */
  .related-letters th:nth-of-type(1),
  .related-letters td:nth-of-type(1) {
    width: 25%;
  }
  /* letter description */
  .related-letters th:nth-of-type(2),
  .related-letters td:nth-of-type(2) {
    width: 75%;
  }
}