No, it's the screen resolution of newer hardware have increased from 1K to 8K.
That actually has very little to do with it.
Screen size and pixel density are two separate things - a 4K monitor has higher pixel density, but that doesn't mean icons and toolbars are smaller, it just means they get rendered at higher resolution.
Now I think about it, they should stop using fixed pixels for toolbar
You're thinking of device pixels.
The px unit in CSS does not represent physical pixels - that's why the rarely-used dpx unit was introduced, for those extremely rare cases where you do want to define the size of something in physical device pixels.
The px unit in the browser gets scaled up, depending on your operating system settings - of course, you can configure your operating system DPI setting such that browsers will render px units as physical pixels, but on an 8K monitor, your mouse pointer would be like 2 millimeters tall and you would need a microscope to even read the text. 😅
Monitors and operating systems of course do not use those settings by default - and the idea of increasing pixel density is not about cramming more content onto the screen, it's about improving fidelity. To achieve that, everything is scaled up by default. Yes, even px units in a browser. 🙂
The changes I made aren't mainly about size, they're about rhythm, grouping and structure.
