chromium/third_party/blink/web_tests/wpt_internal/printing/default-margins-001-print.html

<!DOCTYPE html>
<link rel="match" href="default-margins-001-print-ref.html">
<script>
  if (window.testRunner) {
    testRunner.setPrintingMargin(33);
  }
</script>
<style>
  @page :first {
    margin: 100px;
  }
  body {
    background: yellow;
  }
</style>
Large margins on the first page.
<div style="break-before:page;">
  Default margins on the second page.
</div>