The other thing I did with my code above was get rid of the <center> tag -- deprecated since XHTML 1.0 strict (?), and completely unsupported in HTML5 -- futureproofing...
Since my previous code was "unique" here's more or less the same thing that validates for HTML5:
font-family:Georgia, "Times New Roman", Times, serif;
<iframe id="display" name="display" width="300" height="300" seamless src="Photo96.png"></iframe>
<a href="Photo97.png" target="display">Get Photo97</a>
<a href="Photo98.png" target="display">Get Photo98</a>