CSS Media Queries Level 5 introduced two new queries: dynamic-range and video-dynamic-range. Both have similar wording, and currently the wording for dynamic-range is like so:

dynamic-range represents the combination of max brightness, color depth, and contrast ratio that are supported by the UA and output device.

high
The combination of the User Agent and the output device fulfill all of the following criteria:

• it has a high peak brightness
• it has a high contrast ratio
• its color depth is greater than 24 bit or 8 bit per color component of RGB

standard

• One or more of the criteria for a high dynamic-range is not fulfilled.

The way Safari has implemented this media query is to make @media (dynamic-range: standard) checks always pass, and @media (dynamic-range: high) check against the capabilities of the current display device. This makes sense from a future-proofing perspective, as standard can be seen as a subset of high, and if ultra-high dynamic-range displays are ever introduced, high should be a subset of that.

However, the wording of the standard enum makes it sound as if standard and high should be mutually-exclusive. I think we should change this wording to reflect standard as a subset of high.

Additionally, the wording of "The combination of the User Agent and the output device..." has caused some confusion about what the capabilities of the user agent must be in order for the high query to pass. In the discussion surrounding the proposal for these queries, the idea was that this query would be a coarse representation of the display device's capabilities, and more detailed APIs such as MediaCapabilities could be used to gather specific information about the User Agent's capabilities for specific purposes. I think we should remove mention of the UA in the description of this media query to clarify this confusion.