I remember working for a client who needed to support IE6 (with all the insane bugs/quirks/limitations) and I’d despair every time the designers would hand over a Photoshop design with rounded corners. They also needed it to be responsive (at the time mostly just different desktop sizes). Would usually require cutting the corners out and positioning them in table cells. There’s a certain amount of dev resilience you build having to do stuff like that by hand!
We worked with an internal design team, but basically just one UX specialist who has zero comprehension of how HTML, CSS or and web related technologies worked. At one point we where meet with "I don't like that the site blinks!" ... What do you mean by "blinks", we built it, it doesn't blink. Turns out she didn't like that that switching pages would cause the browser to load the next page and in turn there would be an ever so brief moment where the browser would show a blank page while loading the next page. This was in the initial ASP.NET and Ajax days, to the end result was "wrap the whole damn thing in an update panel".
For those who doesn't know the ASP.NET update panel was basically HTMX before HTMX. The browser would do a background request and replace the content of the update panel with the html returned by the background request. Normally you'd just use if for a form submit, e.g. like a comment box. The user puts in their comment, the backend return all the comments, including the new one and the browser replace the current list of comments with the new one. We essentially put the entire site in to the update panel.
Even though it was a long time ago I still have IE6/7 workarounds burned into my brain, most of them float related but also having a whole stylesheet for that damn browser... <!--[if lte IE 6]>: