I don’t use Safari so I can’t give you specific directions but I’m sure you can google for “disable safari extensions” to figure out how to view and disable extensions. Or, if you have another browser on your computer you could try using it instead. Your CSS code is correct so that’s why I think it is an extension issue. You are going to run into this problem quite a bit so you’ll definitely want to fix it now.
I tried turning dark mode off in MacOS, but Safari didn’t even change to light mode even though another app I had open did, I think it’s how Safari responds dynamically based on the color theme of the website that is keeping the colors dark and interfering with the check. This is an almost stock install MacOS. No extensions installed in Safari, still had this issue. Downloading Google Chrome and doing challenge 49 as instructed finally passed though.
The instruction for 49 is explicit and straightforward, perhaps a regex match or something similar to check for the expected string would work better in some cases like this one? Otherwise some attention might need to be paid to the color scheme of the website for Safari users.
I encountered the same issue on step 49. After making sure that my code is correct and all my extensions were turned off, I repeatedly tried executing the code but no luck. So I glanced through the forum only to figure out that I’m not the only one stuck here. Safari is noticeably more apparent to these kind of issues as I’ve also faced the same in previous chapters, but disabling the extensions fixed that. At last, I signed in on my phone’s browser and cleared the step in first attempt. I recommend the same.