<!DOCTYPE html>
<html>
  <head>
    <title>subscript</title>
    <meta charset="utf-8"/>
  </head>
  <body style="background: #5f5; font-size: 50px;">

    <div>
      <math>
        <msubsup>
          <mi mathbackground="#5f5">f</mi>
          <mspace id="s0" width="50px" height="50px" mathbackground="blue"/>
          <mspace id="s1" width="50px" height="50px" mathbackground="blue"/>
        </msubsup>
      </math>
    </div>

    <br/>

    <div>
      <math>
        <mmultiscripts>
          <mi mathbackground="#5f5">f</mi>
          <mspace id="s2" width="50px" height="50px" mathbackground="blue"/>
          <mspace id="s3" width="50px" height="50px" mathbackground="blue"/>
          <mspace id="s4" width="50px" height="50px" mathbackground="blue"/>
          <mspace id="s5" width="50px" height="50px" mathbackground="blue"/>
          <mspace id="s6" width="50px" height="50px" mathbackground="blue"/>
          <mspace id="s7" width="50px" height="50px" mathbackground="blue"/>
        </mmultiscripts>
      </math>
    </div>

  </body>
</html>