iCloud Mail is in dark mode and there is no "customize"

Customize and use the homepage tiles on iCloud.com - Apple Support

Customize the appearance of iCloud.com - Apple Support

I attempted to follow the instructions on these two pages but there is no "Customize" text or link on my homepage. My iCloud Homepage and Mail are in dark mode and I can't find a way to switch it to Light mode. Likewise there is nothing in iCloud Mail Settings or any other screen that I can find.

Now I find elsewhere that you can switch your macBook to Dark/Light/Auto to get Safari and iCloud to use that setting. This Apple documentation is either completely out of date or something is broken, e.g. how to Customize iCloud page using links on that page which is stated in the documentation?

[Edited by Moderator]