Save complete rendered web page's entire DOM and CSS styles only

I have a need to write tests against a rendered web page. However, getting to the testable screen takes very complicated steps. These include:

• Logging in
• Clicking in many different places in certain ways

I considered headless browser solutions like puppeteer or selenium but these will blow up the complexity of tests too much.

Is there a way for me to manually perform these steps to produce the page to look certain way I want to test in and save only the page's current DOM structure and entire CSS styles rendered? I only need to re-create (using puppeteer or selenium) the DOM and CSS state of that instant in time to repeatedly test different code against it.