w3c / w3c/csswg-drafts

[css-env] Device Pixel Ratio

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Description

As a result of #614, please add environment variables:

  • env(device-pixel-ratio)
  • env(device-pixel-ratio-x)
  • env(device-pixel-ratio-y)

This is a <number> constant, which can be used verbatim as a multiplier or divisor with a <length>, e.g. calc(1mm * env(device-pixel-ratio, 1)), to get from nominal, CSS millimeters to actual, SI millimeters etc.

On media and devices where px depends on physical units and not the other way around (as on screens), this should always be set to 1.0. Elsewhere, it should not deviate a lot from this.

I included horizontal and vertical variants, because not all pixels are square.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reading the discussion linked from issue #614 and the requirements in this issue. Determine where the CSS Environment Variables specification defines environment variables and how a constant is specified. Done means the three device-pixel-ratio variables are defined with their horizontal and vertical behavior and fallback usage clearly resolved.

Written by the indexing model from the issue text.

Assessment

Tech stack
css
Domain
frontend
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
32/100

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