Progressively enhancing Grid Lanes

This post is a follow-up on my previous post. I was wondering whether it's safe to use Grid Lanes today. I came up with a solution I find okay, but there is a caveat. Note: This post contains interactive demos. If you want to see them instead of screenshots, enable the CSS Grid Lanes Layout flag in Edge or Chrome or use Safari 26.4+ or Polypane 29+. In my last blog post, Your Grid Lanes will likely fail WCAG 2.4.3, I explained how Grid Lanes are inherently inaccessible by default unless you take extra measures. I also concluded that it's probably only safe to use Grid Lanes with Reading Flow. According to Rachel Andrew, Google Chrome also made sure to first ship Reading Flow and then Grid Lanes. Unfortunately, that's not what all browsers did. Safari shipped it, but doesn't support Reading Flow yet. Is it a big deal? Now you may think it's not a big deal because most people won't use Grid Lanes anyway until all browsers support it, and maybe, when that happens, Safari will also…