I believe the intention of that statement is to not assume that it's filling the entire screen, that is, not to count on it in some manner. A lot of people sti

I believe the intention of that statement is to not assume that it's filling the entire screen, that is, not to count on it in some manner. A lot of people still make this mistake one way or another. In about the last year I finally gave up; my tiling window manager used to have the browser at 2/3rds the screen with the remaining 1/3 a terminal, but more and more I've been encountering websites that are very unhappy with that width; not small enough to kick in mobile mode or they detect that I'm on a desktop browser and don't adjust, but not large enough for the design they serve me, creating overlapping regions, or horizontal scrolling, etc. So my browser is full screen a lot more often now. On the one hand I'm annoyed, but on the other, an implication of the article is that you essentially can't test at "all" viewport sizes anymore and it's just so easy to accidentally write a website that is unhappy at exactly pixel widths 892-945 when used with my exact font setup and/or zoom setting that I can't really stay mad at some of these sites. Some of the sites I have trouble with are clearly trying, and are competent in many other ways. You can hardly expect your designers to visit every page on your site and test every single width from 200 to 2000 one pixel at at time, let alone ask them to do it again with a variety of zoom settings. Heck, I can't even tell you my own website can do that. I've checked it on a phone and in my desktop browser at a couple of sizes, but I can't do it anymore than anyone else can nowadays.