css-inherit-fn/tests/es6/test.html

Sass and Less mixins to enable CSS --var: calc(inherit(--var) + 1);

<script>
  const exports = {}
</script>
<script src="../helpers.js"></script> // adds normalizeWhitespace to the global scope
<script>
  const waitForIt = fetch('../test.compiled.css')
   .then(response => response.text())
   .then(data => {
     const style = document.createElement("style")
     style.innerHTML = normalizeWhitespace(data)
     style.id = "expected-css"
     document.body.appendChild(style)
   });
</script>

<script type="module">
  import { buildInherit } from "../../css-inherit.js"
  const style = document.createElement("style")
  let built = buildInherit(
    '.hue',
    12,
    '--hue: calc(inherit(--hue, 0deg) + 30deg)'
  )
  built += buildInherit(
    '.depth',
    12,
    '--depth: calc(inherit(--depth, 0) + 1)'
  )
  built += buildInherit(
    '.swap-hue',
    24,
    '--hue: calc(inherit(--hue, 0deg) + 30deg)',
    '--bg-lightness: inherit(--fg-lightness, 50%)',
    '--fg-lightness: inherit(--bg-lightness, 0%)',
    '--font-size: calc(inherit(--font-size, 2rem) * 0.92)',
    '--border-radius: calc(inherit(--border-radius, -50% / 24) + 50% / 24)'
  )
  built += buildInherit(
    '.has-sticky',
    6,
    '--sticky-z: max(1, inherit(--sticky-z, 7) - 1)',
    '--sticky-add: 0px',
    '--sticky: calc(inherit(--sticky, 0px) + inherit(--sticky-add, 0px))'
  )
  style.innerHTML = normalizeWhitespace(built)
  style.id = "built-result"
  document.body.appendChild(style)

  waitForIt.then(_ => {
    const expectedCSS = document.getElementById("expected-css").innerHTML
    const builtCSS = document.getElementById("built-result").innerHTML
    const justDoItMyself = expectedCSS === builtCSS && (10000 === Math.min(10000, builtCSS.length))
    document.body.style.backgroundColor = justDoItMyself ? "green" : "red"
  })
</script>