--inch

A :root{} level --inch poly-fill for accurate implementation of the Standard (SI System) and the Imperial Units of Physical Measurement using CSS Custom Properties. This poly-fill includes a list of exact pixels:--inch pairings (or mappings) for the commonly available consumer hardware.

PRs are welcome.

Pairing?

A pairing maps the device resolution dpi to the actual size of an inch that has been measured physically using a scale. A detailed article on how this works is printed on the Bubblin blog.

Usage

1. Using --inch with Toucaan

If you are using Toucaan, you can simply add the --inch.css poly-fill as part of the utility variables adopted in the critical css region of your webpage. Alternatively, --inch can also be directly imported into the env source of the framework by simply copying the poly-fill files into the appropriate folder.

  /* Import the `--inch` variable. */
  @import url('path/to/--inch.css') only screen;

  /* Portrait ⇋ landscape switch. */
  @import url('/dist/portrait.css') only screen and (orientation: portrait);
  @import url('/dist/landscape.css') only screen and (orientation: landscape);

  :root {
    /* Other CSS variables are specified here… */

  }

Additional Units

The following absolute units can also be used with the inch variable:

:root {
  /* Import the `--inch` variable. */
  @import url('path/to/--inch.css') only screen;

  --centimeters: calc(2.54 * var(--inch));
  --millimeters: calc(25.4 * var(--inch));
  --meters: calc(2.54 * var(--inch) / 100);
  --feet: calc(12 * var(--inch));
  --thou: calc(var(--inch) / 1000); /* …because why not!? */
}

2. Using the --inch unit with Bootstrap, Bulma, or Tailwind:

It might work, but my general recommendation is to avoid using the --inch poly-fill with any of the responsive css frameworks. Mainly because:

1. The poly-fill is experimental in nature.
2. Responsive design is rooted in the use of standard design units like px, em etc.

3. Using the --inch variable with plain css:

The --inch poly-fill is great for apps that do not use any css framework. It works great with vanilla css!

NOT FOR PRODUCTION USE

Although this poly-fill has a certain level of support for common consumer devices already, it certainly is NOT SUITABLE FOR PRODUCTION USE at all. At least not yet.

Assuming support, you will be able to use the --inch on your styles, like so:

/* Portrait CSS */
@media (max-width: calc(2 * var(--inch)) {
  body{
    /*  Style for smartwatches or a very tiny mobile screen go here. */
  }
}

@media (min-width: calc(2.000000000001 * var(--inch)) and (max-width: calc(4 * var(--inch))) {
  body{
    /* Smartphones and phablets in portrait mode.*/
  }
}

@media (min-width: calc(4.000000000001 * var(--inch))) and (max-width: calc(8 * var(--inch))) {
  body{
    /* Tablets and larger menu surfaces in portrait mode.*/
  }
}

/* …and so on. */

Contribution

Contributions of new mappings are always welcome. Head over here to learn how. 🙏🏻

References

1. https://caniuse.com/#feat=css-media-resolution

2. https://caniuse.com/#search=device-width

3. https://sebastien-gabriel.com/designers-guide-to-dpi/

4. https://www.w3.org/Style/Examples/007/units.en.html

5. https://bubblin.io/blog/web-design-recommendations-for-the-apple-watch

Do share your thoughts on GitHub