I'm still thankful every day for the fact that most websites are built on an HTML DOM that is so friendly to introspection and hacking. Given the directions the rest of mainstream computing is going it feels like a miracle that we got that and it has held on for so long.

JavaScript and CSS have mutated dozens of distinct dialects from different periods of time yet today they all still work together harmoniously.

The level of dedication browser engines have toward maintaining backward compatibility is pretty astonishing.