> Although paper handouts obviously have a pure white background, the web is better served by the use of slightly off-white and off-black colors. Tufte CSS uses #fffff8 and #111111 because they are nearly indistinguishable from their ‘pure’ cousins, but dial down the harsh contrast.
I never got this argument.
I can see an argument for "We need to reserve some headroom and footroom for Darker Than Common Black and Brighter Than Common White for occasional emphasis scenarios. Or, for differentiation from pure black/white in images and background elements."
But, I read "dial down the harsh contrast" as "We presume users have their monitor contrast settings set too high and intentionally use a reduced range to compensate for their mistake even though it costs us a bit of color precision."
Meanwhile, I might have an LCD monitor with the contrast dialed down next to an OLED with the brightness and contrast cranked up. And, even if the common case user setup is not so extreme, it still varies wildly in practice.
As a game engine developer, this is something I've had to deal with in practice for a long time... Reduced contrast range as a stylistic choice can be quite valid. But, trying to predict user viewing conditions is wishful thinking.
The author's conclusion is flawed: paper and ink are never truly pure white or black. Perfect white/black exists only in digital spaces, while physical materials always have subtle variations in tone and color.
I think that's sort of what the author is getting at, if expressing imperfectly -- when you look at black ink on white paper, you're almost certainly not seeing a physical embodiment of #000000 on #FFFFFF. I tend to think moving at least one of the two colors off "pure", if not both, makes pages look more pleasant. (To stave off people leaping in to say "you web designers hate contrast," I'm not talking about moving to light gray on slightly less gray; it's not difficult to keep well above the WCAG's 7:1 AAA-level contrast ratio while bringing things down just a notch.)
Not using #000000 for background black removes an opportunity for your site to look awesome on OLED screens.
As far as I can tell, OP's argument is bullshit. I did a bunch of research into max contrast displays and haven't found any reason to not use them. There are reasons to not use max _brightness_ since a bright screen can be problematic in the dark, but it's better to use max contrast on a slightly dim screen than to use max brightness with a slightly lower contrast.
There was some minor effects for people with dyslexia and high contrast, but no science-backed a11y guidelines provide evidence of reducing contrast for the general population. And since most people have crappy cheap screens instead of fancy Macbooks that UI designers use, reducing contrast makes it worse for them. Particularly at off-screen angles.
I'm not sure who started this UI trend of grey-on-gray, but it's shitty and should be avoided unless there is an intentional stylistic reason to sacrifice form for function.
Contrast is a silly setting to even have for displays. Step #1 for decent monitor and TV calibration is always to set contrast to max anyway.
> Although paper handouts obviously have a pure white background
This alone makes it clear enough they’re not going to make much sense.
As far as I am aware there is nothing “pure” white, or at least, nothing you’re going to print on with a laser printer.