Text Color Adjustable

cawa-93 opens #171 with white text on black at a 21:1 ratio, which passes 1.4.6 Contrast (Enhanced) at AAA and is, in their words, absolutely not readable, and proposes a maximum alongside the minimum. NathanInnes offers Twitter's branding revamp as a case in point: it passed beyond the standard and a lot of users found it difficult to read and straining on the eyes.

JAWS-test finds high-contrast text readable in itself, accepts that some people struggle with it, and argues the fix is for colour adaptation to user needs to work well and for WCAG to support that adaptability via custom styles, Windows High Contrast Mode and similar. mraccess77 says a contrast maximum would negatively affect them personally while acknowledging others need low contrast, and concedes specific bad combinations exist — small white text on black being one — before asking whether a better calculation than current contrast could isolate those cases, pointing at Myndex's work.

Myndex's objection in #171 is that WCAG 2 contrast math is not perceptually accurate — it already overstates minimum contrast for dark colours — so building a cap on it would produce more unreadable pages, not fewer, and entrench the misunderstanding of how contrast and readability work. Reframes the problem as excess luminance rather than excess ratio: users crank screen brightness to cope with all the low-contrast content in the wild, then get blasted by a site with good contrast. Also notes the OP's own example is too small and too crowded to be evidence. bruce-usab agrees white on black is a common barrier but cannot see how to address it in WCAG 2.x even at AAA, since the same rule would flag plain black-on-white body text, and points to APCA as the WCAG 3 route.

The 2023 status update separates the cases: no maximum contrast in light mode, only a maximum luminance, which is a user display control rather than an author one, with paper-emulation best practice of keeping body-text background at about 85 percent of the adaptation state. Dark mode is different — excessively bright text on dark backgrounds causes halation and glare — and names interim experimental values under study of Lc -90 maximum for body text and Lc -85 for larger text, using APCA 0.0.98G4g. Adds that there is room for at least two dark schemes, day and night, and that daltonised, photophobia and Meares-Irlen schemes will likely need their own maxima.

Reports from a calibrated setup — displays at 150 cd/m2 white luminance, room illuminance around 100 lx, IPS LCD at roughly 1000:1 static contrast — that black on white is comfortable while white on black remains practically unreadable, partly from halation due to astigmatism. Finds Lc -90 uncomfortable and would want something nearer Lc -50 for light-on-dark. Also warns the fix cuts both ways: in a properly calibrated environment, an author lowering contrast for dark text on light backgrounds reduces readability, comparing blue on brown to printing on kraft paper rather than white.

emanser869's #178 proposes adding to 1.4.8 that foreground and background colours can be adjusted by the user to apply uniformity of contrast.

utkudyn-a11y's #618 asks that captions carry at least 4.5:1 between caption text and its background as a core requirement, in addition to the supplemental captions-adjustable requirement, because caption legibility directly affects partially sighted and low-vision users.