> I'm concerned this will have a nontrivial impact on browser layout performance. I've experienced this with iOS Safari. I was experimenting with different lay

> I'm concerned this will have a nontrivial impact on browser layout performance. I've experienced this with iOS Safari. I was experimenting with different layout methods, and at one point a display:grid didn't get deleted, and some days later when I was testing with Safari it was taking at least half a second to render a page. I'm talking 5 paragraphs of text, possibly with subgrid I was experimenting with, nothing crazy. I had no idea CSS could ever get that so slow and I thought it had to be something with React, and it took way longer than it should have to narrow it down to that single property.