Oh now i understand,
You're talking about when your fleet is taking lots of casualties,You find that by hovering the number of your ships bottom middle
no,no, no we're (at least what i think) talking about building or repairing a ship, and because the health bar numerator constant changes (building, repairing) and due to the width of each number is different, causes the numerator, demoninator and health percentage to constant jump around. You find that by hovering an individual ship at the bottom left, with the other stats such as attack and all
way to fix it is make them all individual spots that won't get affected by the other's number
though your idea of changing that is also cool too, but not critical at all, infact doesn't need changing.