I am sure not surprised learning for the second time that the first bitcoin block Explorer was built by theymos, I've read about this outside this forum one time, and that was even how I discovered this forum.

And from the look of the first bitcoin block Explorer as shown in the shot you posted, I do not think a lot changed so far, aside from background and text designs, fonts, more css properties, more functionalities through programming languages used.

Alot of the changes will probably be in the back end, for the front end, it's possibly still the same arrangement with little or minor readjustments here and there.

All the same, kudos to how far technology have brought us.