From battlecruiser (top) to fast battleship (bottom).
She's still only got 8 inches of belt and 10 inches of turret and barbette armor.
That's slightly better than Jutland-era battlecruisers and "modern" heavy cruisers, but much worse than any contemporary battleship and in fact vulnerable to 8 inch guns at close range. It's not implausible to believe Hiei suffered belt penetrations during the naval battle of guadalcanal.
Sometimes I hear that my own and Hiei's appearances changed too much when we are remodelled to Kai NiIn the first place, it's a historical fact that the Kongou class underwent a drastic change in appearance DEEE-SUKongouinitialKongoufinal