chromium/chrome/browser/resources/print_preview/print_preview.html

<!doctype html>
<html dir="$i18n{textdirection}" lang="$i18n{language}" class="loading">
<head>
  <title>$i18n{pageDescription}</title>
  <meta charset="utf-8">
  <meta name="color-scheme" content="light dark">
  <base href="chrome://print">
  <style>
    html {
      background: white;
      /* Remove 300ms delay for 'click' event, when using touch interface. */
      touch-action: manipulation;
    }

    @media (prefers-color-scheme: dark) {
      html {
        background: rgb(40, 41, 44);
      }
    }

    html,
    body {
      height: 100%;
      margin: 0;
      overflow: hidden;
      width: 100%;
    }

    .loading body {
    }

    .loading body::before {
      background: rgb(218, 220, 224);  /* --google-grey-300 */
      border-bottom-width: 0;
      border-color: rgb(232, 234, 237);
      border-inline-end-width: 1px;
      border-inline-start-width: 0;
      border-style: solid;
      border-top-width: 0;
      content: '';
      display: block;
      height: 100%;
      width: calc(100% - 385px);  /* --print-preview-sidebar-width */
    }

    @media (prefers-color-scheme: dark) {
      .loading body::before {
        background: rgb(95, 99, 104);  /* --google-grey-700 */
        border-color: rgba(40, 41, 44, .9);
      }
    }
  </style>
</head>
<body>
  <print-preview-app></print-preview-app>
  <link rel="stylesheet" href="chrome://resources/css/text_defaults_md.css">
  <link rel="stylesheet" href="chrome://resources/css/md_colors.css">
<if expr="is_chromeos">
  <link rel="stylesheet" href="chrome://theme/typography.css">
</if>
  <script type="module" src="print_preview.js"></script>
</body>
</html>