> I was working on top of a huge CSS framework
Well, that's the whole thing then, isn't it? The huge CSS framework probably had tons of hacks (as you say) to make things work in IE8... it's a bit disingenuous to say you wrote everything to be clean and without browser hacks, if the hacks all exist but are buried under a "huge CSS framework".
Your whole experience could probably be restated as "I was working with a CSS framework that did a bunch of cross-browser hacks for me, and the tweaks I made to it didn't work in safari", which is a pretty uninteresting statement, because it's equally likely that any issues you had in safari are the fault of the CSS, and not the browser. (In fact, much much more likely.)
I was working on top of a huge CSS framework - the majority of styling work I did was tiny tweaks to styles where the appropriate hacks had already been solved.
Also I didn't mention layout. The specific pain point was contenteditable in combination with JS - by the time I got to the code everything surrounding my little problem-space had been solved by the rest of the team. Again, specifically, Safari demonstrated wildly different behavior within that specific space, where other browsers only behaved marginally different (a relative term, contenteditable is a complete mess, sadly, still in HTML5) in a way that I could find a viable subset of functionality that worked consistently.