How to inherit the font styles from the parent of an iframe

How to inherit the font from the parent of an iframe.
If this is impossible, what could be the alternative?

I maintain a small website. The main menu looks like this:

<!DOCTYPE html>
<html lang="nl">
  <meta charset="utf-8">
  <title>Container for iframe</title>
  <style>
    html, body, #main   { height: 100%; }
    iframe              { height: 100%; width: 100%;}
    body, #main         { font-family: sans-serif; }
    #main               { background-color: azure; }
    iframe, #main       { height: 100%; width: 100%; }
  </style>
  
  <p>Container for iframe</p>
  <p><a href="choice-1.html" target="content">Inherit font from iframe</a>
  <p><a href="choice-2.html" target="content">Choice two</a>
  
  <div id="main" style="background-color: azure; color: red">
   <p>Show iframe below:
   <iframe name="content" src="choice-1.html">
    <p>Fall back.
   </iframe>
  </div>
</html>

This is the html of the child page:

<!DOCTYPE html>
<html lang="nl">
<meta charset="utf-8">
<title>Test</title>
<style>
html, body {font-family: inherit;}
</style>
<h1>I am choice one</h1>
<p>I try to inherit the font from my parent, but failed...
</html>

The problem is that the website should be manageable by someone with limited knowledge of html, css and javascript. A simple solution would be appreciated.