You can see that even on this website, if you click "Debug Mode" (top right) and notice that later in the page, the headings and body copy begin to drift out of vertical alignment (against the background grid).
But so much time is being wasted on developers fine tuning magic numbers that the browsers are extending CSS to automatically fix the font developer's mistakes.
https://github.com/jantimon/text-box-trim-examples
You can see that even on this website, if you click "Debug Mode" (top right) and notice that later in the page, the headings and body copy begin to drift out of vertical alignment (against the background grid).