CSS: “high” is not a “prefers-contrast” value

A non-standard value high is being used for the prefers-contrast media feature in a <style> block or style attribute, but the valid values are no-preference, more, less, and custom.

The prefers-contrast media feature detects whether the user has requested more or less contrast through their operating system or browser settings. Early drafts of the specification used high and low as values, and some older references still mention them. The current specification replaced these with more and less.

The W3C validator flags high because it checks CSS within HTML documents against current standards. Even though some browsers may still accept high as an alias, it is non-standard and should be replaced with more.

The mapping from old to new values:

• high → more
• low → less

HTML example with the issue

<style>
  @media (prefers-contrast: high) {
    body {
      background: white;
      color: black;
    }
  }
</style>

Fixed example

<style>
  @media (prefers-contrast: more) {
    body {
      background: white;
      color: black;
    }
  }
</style>

Learn more:

MDN Reference

CSS prefers-contrast media feature - MDN

→

MDN Reference

CSS Media Queries Level 5 - MDN

→