Of course evening and morning are indefinite. Even now, the time of darkness and light changes with the seasons.
Genesis is a conception of inspired but unscientific writer/s who did not understand any science. They did not know about tilt of the earth, that the stars were actually other suns far away or that the earth was round.
Genesis 1 is Hebrew poetry. Poetry has a lot of symbolism, analogy and other structures like Hebrew thought poetry that make it unlikely to be literal.
But when taken in a more reasonable manner Genesis comes fairly close to science considering when it was written.
When God said "let there be light" all things could have been created through Einsteins conversion of matter and energy.
The sequence of life appearance, while not precise, does give an indication of the evolution process we observe.
I see no value in holding religious beliefs that are contrary to fact. Apparently, the creationists are convinced that believing nonsense brings them closer to God.
I think they just give God a good laugh.
If you cant even see that when someone says Morning, Evening, a full day
means a 24 hour day, then I am wasting my time.
You need to ractice reading comprehension.