css/css-conditional/at-supports-046.html

<!DOCTYPE html>
<html lang="en">
<meta charset="UTF-8">

<title>CSS Conditional Test: Unknown Functional Notation as False in @supports</title>
<meta name="assert"
      content="Test passes if unknown but grammatical functional notations are treated as false in @supports.">
<link rel="help" href="https://www.w3.org/TR/css3-conditional/#at-supports">
<link rel="author" title="Elika J. Etemad" href="http://fantasai.inkedblade.net/contact">
<link rel="match" href="at-supports-001-ref.html">

<style>
  div {
    background: green;
    height: 10px;
    width: 100px;
  }

  div {
    background: red;
  }

  @supports not unknown() {
    .test1.bare { background: green; }
  }
  @supports (not (unknown())) {
    .test1.wrapped { background: green; }
  }

  @supports not unknown(with stuff) {
    .test2.bare { background: green; }
  }
  @supports (not (unknown(with stuff))) {
    .test2.wrapped { background: green; }
  }

  @supports not unknown(!@#% { ... } more() @stuff [ ]) {
    .test3.bare { background: green; }
  }
  @supports (not (unknown(!@#% { ... } more() @stuff [ ]))) {
    .test3.wrapped { background: green; }
  }

  .test4, .test5 { background: green; }

  @supports unknown() {
    .test4.bare { background: red; }
  }
  @supports (unknown()) {
    .test4.wrapped { background: red; }
  }

  @supports unknown(with stuff) {
    .test5.bare { background: red; }
  }
  @supports (unknown(with stuff)) {
    .test5.wrapped { background: red; }
  }
</style>

<p>Test passes if there is a <strong>filled green square</strong> and <strong>no red</strong>.</p>

<div class="test1 bare"></div>
<div class="test2 bare"></div>
<div class="test3 bare"></div>
<div class="test4 bare"></div>
<div class="test5 bare"></div>
<div class="test1 wrapped"></div>
<div class="test2 wrapped"></div>
<div class="test3 wrapped"></div>
<div class="test4 wrapped"></div>
<div class="test5 wrapped"></div>