I did some 3d css demos back in 2013. This one got quite popular so maybe you might've seen it:

3D Macbook Air animation: https://codepen.io/neoberg/pen/DEZbKv

This one I think is more impressive but doesn't look as beautiful: https://codepen.io/neoberg/pen/DEwwNE

edit: Forgot about this one. https://codepen.io/neoberg/pen/doVQqv