Let the browser measure it
A site built last year with a perfectly good image pipeline was still sending the 1600px file to a phone, and it turned out to be the same missing attribute I wrote a whole post about in 2018.
5 posts filed under Responsive, newest first.
A site built last year with a perfectly good image pipeline was still sending the 1600px file to a phone, and it turned out to be the same missing attribute I wrote a whole post about in 2018.
A client dragged a product card out of the main column into their sidebar and the button ended up hanging off the edge of it, because the class that would have laid it out narrow gets applied by a developer and there wasn't one in the room.
Device breakpoints go stale the moment a new phone comes out. We can do better than yet another list of numbers.
Separate "m." sites were a reasonable answer to a 2010 problem, but what finally killed them wasn't technical. It was Google changing what shows up in search.
Flexbox has crossed the line where I can use it on real work, and the surprise isn't the layouts it enables. It's how much of my CSS turns out to have been compensation for not having it.