How many times in our style development have we needed to have elements visually linked to each other? And how many times have we had to wrestle with absolute positions, magic numbers, and sky-high z-indexes? Perhaps by managing the cases where the necessary space isn't available, adding a bunch of JavaScript to the mix, or more likely yet another third-party library in the hope that it respects the design constraints.
Perhaps one of the most anticipated CSS features of recent years, Anchor Positioning API is actually something that would have been extremely useful 20 years ago. Finally arrived in baseline, we'll see what the implications of these new API are, from the most immediate practical examples to the most advanced (much more than just tooltip positioning) and imaginative uses, for increasingly powerful and expressive markup and styles.