Apple love to preach "the UI gets out of the way of your content" with each new redesign, but how true is that in practice? Let's compare the total height of the Safari UI with a toolbar, favourites bar and tab bar visible, across the three latest Mac OS design languages – Yosemite, Big Sur and now Tahoe. I've added a red line for emphasis.
It sure looks to me like the UI is eating more into my content with each redesign.
