first of all, please do not forget, ALHAMDUILLAH, there is no actual connection between solar days and lunar cycles. that said...
Isn't it true that there is a discrepancy regarding how many days are in a month, that is, every other month has an extra day?
It should be beneficent then, to rest from counting to eliminate the difference. That is, between the last visibility of the moon until the next visibility of the moon, these days are not part of either month. They are neither counted with the numbering system the other days are counted with, nor are they charted in a grid with the other days on a calendar graph. to the effect that the month is slightly shorter (as it does not count the time when the moon is not visible) as well as always the same -- no differentiation from one month to the next.
So if the moon goes invisible on july 5th, and remains invisible until july 7th, these two days are not counted on the lunar calendar, but are days of not counting, or sabbaths of counting. A calendar so designed is always 28 days long every month -- what do you think?