Your understanding of yom is incomplete. It is more well defined than the English “day” in fact. Your gripe against the literal view is something you should take up with 3500 years of Judaism. Every Jewish child knows a yom is from sunset to sunrise... Always.
Somebody around here has never checked their concordance nor has performed a word study on the various ways on how yom is translated in the Bible....
See my post 99 if you need a little help.
I presume you made a typo when you said that a yom is from sunset to sunrise. If it wasn't a typo, then why do the Young-Earthers insist, without any grammatical basis, that yom has to mean a literal, 24-hour day -- except where it doesn't?