Having a proper doc type and having a specific IE stylesheet that added zoom:1 property to element could fix a lot of that off the bat and was a simple one to include on a webpage. Transparent PNGs of course wouldn't work (well there was a way but it was an arcane trick and I can't remember it for the life of me now).
TBH I found cross platform development during that time easier than when smart mobile phones came out. There was about 20-30 slightly incompatible forks of the Android Browser/Webkit and the processors were slow and everything was JS. Blackberry OS was still a thing. I also don't miss the problems with iPhone 3GS and 3D background layer flickering.
Also programming cross platform at the time showed me how to write lightening fast JS. That has made me a lot of money when people come to me to fix their crap web apps.
And I’m pretty sure this is where CSS preprocessors were born, right around the time of CoffeeScript and the inevitability of the web being a compilation target.
> Transparent PNGs of course wouldn't work (well there was a way but it was an arcane trick and I can't remember it for the life of me now).
In the recesses of my brain somewhere is a memory that it was related to ActiveX, and/or the CSS filter property. You set some special filter value that invoked ActiveX? Maybe I'm remembering incorrectly but if I think about it too deeply I might start screaming and never stop.
Yup it was something like that. I think it was the opacity property. IE6 required a custom property so in order to do opacity you had to set at least two CSS properties, might have actually been more because Safari/Firefox/Opera/IE mostly had opacity as a CSS extension.
1. The "hidden" element at the root of the IE DOM tree, only accessible with "*" via CSS
2. inline-block was broken on IE6 (but fixable with hacks), and no transparent PNG support.
3. The outline CS property was implemented the same as background in IE
Best of all was the dog slow IE 6 JavaScript interpreter, which was like 50x slower than Firefox and IE 7+.