Old IEs should at least fail *all* the time
I was facing an issue with the IE6-7 box model, so I made the traditional fix: set the width as including the padding. Nope, that just messed up something else.
Turns out that IE uses a better box model if you use a doctype declaration (I only recently got actually good enough at web dev to actually know to use one), so that solved part of it. But it also turns out that its better box model still has some other flaws, such as a child element’s width set at 50% counts the parent element’s padding in that 50%, meaning that they won’t actually both fit on one line.
Old IEs, if you must fail epically, at least do so consistently. Eagerly looking forward to your extinction.