CSS, JavaScript, HTML tùy chỉnh

I'm using Apidog's "Custom JavaScript" feature, which only allows pure JavaScript (no <script> or <style> tags).

Please convert the following code to pure JavaScript. Here are the requirements:
1. Rewrite the <script> tag to document.createElement('script') dynamic creation method;
2. Inject the <style> content into the newly created style tag and insert the head;
3. Please use standard methods (such as createElement, appendChild) for all DOM operations, and do not use document.write;
4. If the original code uses `window.addEventListener('DOMContentLoaded', ...)` or `window.addEventListener('load', ...)` only to wait for the page before running code, remove the event listener and run the code directly. Apidog executes custom JavaScript after the documentation page has been rendered, so the browser's `load` event may already have passed by that time; code registered inside a `load` listener may not be executed;
5. The final generated JavaScript should be able to run directly in the browser without any explanation.

Original code:
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(paste your code here)
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