So, occasionally we see something that skirts the transitional period between the Steam and Diesel eras, basically the "Edwardian" period from ~1900 to the end of WW1. It has its own aestetic that bridges the styles, tech, and philosophies of the two eras.
Early aircraft that look bird- or bat-like, high collars without ties, high boots with laces, sleeker-cut uniforms with rows of ribbons but less ornimentation, dress swords, rumbling riveted machinery as likely to be steam as petrol...
A great example is Leviathan.
So, what to call it? I've heard it called "Edwardianpunk", but that seems so awkward a name.
There seems to be a transitional time between genres that doesn't seem to fit well within either. So maybe the Edwardian Transitional?
Cold War era steampunk?