message: fix(theme): improving accessibility of headers
diff: @@ -7,6 +7,7 @@ th.gridjs {
  user-select: none;
  box-sizing: content-box;
  white-space: nowrap;
  + outline: none;
  &-sort {
  cursor: pointer;
  @@ -15,6 +16,10 @@ th.gridjs {
  &-sort:hover {
  background-color: $gray3;
  }
  +
  + &-sort:focus {
  + background-color: $gray3;
  + }
  }
  &-th:first-child {
  