<!DOCTYPE html>
<html>
  <head>
    <title>displaystyle</title>
    <meta charset="utf-8">
    <link rel="stylesheet" href="/fonts/ahem.css">
    <style>
      math {
          font: 25px Ahem;
      }
    </style>
  </head>
  <body>

    <!-- Test displaystyle on mstyle -->
    <math>
      <mstyle displaystyle="true">
        <munder><mo>O</mo><mo>O</mo></munder>
      </mstyle>
      <mstyle displaystyle="false">
        <msub><mo>O</mo><mo>O</mo></munder>
      </mstyle>
    </math>

    <!-- The mfrac 