The first three days were marked by the separation of light from darkness

Genesis 1:3 NLT

> 
> Then God said, "Let there be light," and there was light.:4 And God saw that it was good. Then he separated the light from the darkness.:5 God called the light "day" and the darkness "night." Together these made up one day.
> 
> 
> 

During the fourth day we get the introduction of other lights,sun and moon which are said would regulate days,years and seasons.

Genesis 1:14-19 NLT

> 
> And God said, "Let bright lights appear in the sky to separate the day from the night. They will be signs to mark off the seasons, the days, and the years.:15Let their light shine down upon the earth." And so it was.:16For God made two great lights, the sun and the moon, to shine down upon the earth. The greater one, the sun, presides during the day; the lesser one, the moon, presides through the night. He also made the stars.:19 This all happened on the fourth day.
> 
> 
> 

By the introduction of sun and moon would this not have changed the length of the
fouth day vis-a-vis the first three days

Were all days equal in length?