css/css-cascade/presentational-hints-cascade.html

<!DOCTYPE html>
<link rel="help" href="https://drafts.csswg.org/css-cascade-5/#preshint">
<link rel="author" title="Xiaocheng Hu" href="mailto:xiaochengh@chromium.org">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
.test {
  height: 100px;
  background-color: green;
}

#target1 {
  width: 100px;
}

@layer {
  #target3 {
    width: 100px;
  }
}
</style>

<img class=test id=target1 width=200>
<img class=test id=target2 width=200 style="width: 100px">
<img class=test id=target3 width=200>

<script>
test(() => {
  assert_equals(getComputedStyle(target1).width, '100px');
}, 'Presentational hints have lower precedence than regular author style sheets');

test(() => {
  assert_equals(getComputedStyle(target2).width, '100px');
}, 'Presentational hints have lower precedence than the style attribute');

test(() => {
  assert_equals(getComputedStyle(target3).width, '100px');
}, 'Presentational hints have lower precedence than layered style');
</script>