Keep text recolorable by the user's browser
Most browsers can override an author's foreground and background colors. G156 is about not standing in the way. Deliver text in a technology those browsers can recolor, which on the web means real HTML text rather than pictures of text, and do not override the reader's choice once they have made it. Check the status before you treat this as a fix. W3C marks G156 sufficient only at the Level AAA visual presentation rule and advisory at both contrast rules, so no Level A or AA criterion can be satisfied with it. W3C adds a caution as well. Replacing the colors of every block of text can wipe out the visual grouping that tells people how a page is organized, so it is a poor fit where background color is what separates one area from another.
How we find it in an audit
Our reviewers apply a user color scheme, a browser high-contrast mode, and a forced-colors setting, then read the page in each. We are looking for text that does not change because it is an image, text that changes into something unreadable, and areas whose meaning collapses once their background colors are replaced.
How affected users experience it
People who set their own colors are not decorating. A yellow-on-black scheme may be the only combination that lets somebody read at all. Light sensitivity, low vision and some cognitive conditions all lead there. Terms published as images of text ignore every one of those settings, so the reader gets a page they cannot alter and cannot read, on the document that matters most.
Passes vs. fails
Passes
The terms are real HTML text, so a reader's dark-background, yellow-text scheme applies to every word.
Fails
Terms and conditions are served as exported images of styled text, so no browser setting can change their colors.
How this gets tested
The W3C publishes test rules that define what a checker looks for here.
- Text has enhanced contrastA tool can check this
- Text has minimum contrastA tool can check this
The other techniques filed under this rule
7 guides on this site are filed under 1.4.3 Contrast (Minimum). W3C lists this one as advisory for that rule rather than sufficient, which means it helps real readers without being accepted as evidence you conformed.
- G18sufficientMeet the 4.5:1 contrast ratio for text
- G145sufficientGive large text at least 3:1 contrast
- G148sufficientLeave text colors default, or set both
- G174sufficientOffer a working switch to high-contrast view
- F24failureNever set text color without its background
- F83failureDo not set text over a low-contrast background image
This guide is our interpretation of W3C technique G156: Using a technology that has commonly-available user agents that can change the foreground and background of blocks of text. W3C publishes its techniques as guidance rather than as the standard, and says so on every one of them. The success criterion is what conformance is measured against, and a technique is one documented way to meet it.