chromium/chrome/test/data/client_hints/style.css

/**
 * Copyright 2021 The Chromium Authors
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
@import url(https://my-site-c.com:44444/nested_style.css);

body {
  font-size: 20px;
}