Flatpickr RTL

style.css

.flatpickr-calendar .dayContainer,
.flatpickr-calendar .flatpickr-weekdaycontainer {
  flex-direction: row-reverse;
}
.flatpickr-month {
  height: 32px;
}
.flatpickr-prev-month {
  left: auto !important;
  right: 0;
  width: fit-content;
  transform: scaleX(-1);
}
.flatpickr-next-month {
  right: unset;
  left: 0;
  width: fit-content;
  transform: scaleX(-1);
}
.flatpickr-day .selected.startRange,
.startRange.startRange,
.endRange.startRange {
  border-radius: 0 50px 50px 0;
}
.flatpickr-day .selected.endRange,
.flatpickr-day .startRange.endRange,
.flatpickr-day .endRange.endRange {
  border-radius: 50px 0 0 50px;
}
.flatpickr-day .selected.startRange + .endRange:not(:nth-child(7n+1)),
.flatpickr-day .startRange.startRange + .endRange:not(:nth-child(7n+1)),
.flatpickr-day .endRange.startRange + .endRange:not(:nth-child(7n+1)) {
  box-shadow: 10px 0 0 #569ff7;
}