chromium/third_party/blink/web_tests/external/wpt/css/css-anchor-position/position-try-custom-property.html

<!DOCTYPE html>
<title>Variable substitution in @position-try rules</title>
<link rel="help" href="https://drafts.csswg.org/css-anchor-1/#fallback">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/check-layout-th.js"></script>
<script src="support/test-common.js"></script>
<style>
.cb {
  position: relative;
  width: 195px;
  height: 70px;
  background: yellow;
  border-bottom: 1px solid black;
}
.spacer {
  width: 1px;
  height: 20px;
}
.anchor1 {
  anchor-name: --a1;
  margin-left: 45px;
  width: 100px;
  height: 30px;
  background: blue;
}
.target {
  position: absolute;
  position-try-fallbacks: --fallback1;
  width: 40px;
  height: 15px;
  margin: 5px;
  background: orange;
  --left: anchor(--a1 right);
  --top: anchor(--a1 top);
}
.fallback1 {
  position-try-fallbacks: --fallback1;
}
.fallback2 {
  position-try-fallbacks: --fallback2;
}
@position-try --fallback1 {
  /* Position to the right of the anchor. */
  left: var(--left);
  top: var(--top);
}
/* Same as above, but using a shorthand. */
@position-try --fallback2 {
  inset: var(--top) 0px 0px var(--left);
}
</style>
<body onload="checkLayoutForAnchorPos('.target')">
  <div class="cb">
    <div class="spacer"></div>
    <div class="anchor1"></div>
    <div class="target fallback1"
         data-offset-x=150 data-offset-y=25></div>
  </div>
  <div class="cb">
    <div class="spacer"></div>
    <div class="anchor1"></div>
    <div class="target fallback2"
         data-offset-x=150 data-offset-y=25></div>
  </div>
</body>