<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8"/>
    <title>&lt;mo&gt; movablelimits</title>
    <style>
      math, math * {
          font: 25px/1 Ahem;
      }
    </style>
    <link rel="stylesheet" type="text/css" href="/fonts/ahem.css" />
  </head>
  <body>
    <math>
      <msub>
        <mo lspace="0px" rspace="0px">+</mo>
        <mn>1</mn>
      </msub>
      <msup>
        <mo lspace="0px" rspace="0px">+</mo>
        <mn>1</mn>
      </msup>
      <msubsup>
        <mo lspace="0px" rspace="0px">+</mo>
        <mn>1</mn>
        <mn>2</mn>
      </msubsup>
    </math>
  </body>
</html>