People use JavaScript for styling? Gross. Never liked JS, it’s necessary for some things but I don’t get building a 10mb site when a 0.1mb site is HTML/CSS would suffice.
Remember building for IE4/5 and had to check everything looked good with out JS because a lot of people had it disabled.
Have you looked at this?: https://dortania.github.io/OpenCore-Legacy-Patcher/ I used it on my 2015 iMac and it runs the latest OS well.