This is a straight-forward project.

Pydoc currently generated 1990's style html which mixes content and presentation, making it very difficult for users to customize the appearance of the output.

It is full of html like:

<table width="100%%" cellspacing=0 cellpadding=2 border=0 summary="heading">
<tr bgcolor="%s">
<td valign=bottom>&nbsp;<br>
<font color="%s" face="helvetica, arial">&nbsp;<br>%s</font></td
><td align=right valign=bottom
><font color="%s" face="helvetica, arial">%s</font></td></tr></table>
    ''' % (bgcol, fgcol, title, fgcol, extras or '&nbsp;')

    def section(self, title, fgcol, bgcol, contents, width=6,
                prelude='', marginalia=None, gap='&nbsp;'):
        """Format a section with a heading."""
        if marginalia is None:
            marginalia = '<tt>' + '&nbsp;' * width + '</tt>'
        result = '''<p>
<table width="100%%" cellspacing=0 cellpadding=2 border=0 summary="section">
<tr bgcolor="%s">
<td colspan=3 valign=bottom>&nbsp;<br>
<font color="%s" face="helvetica, arial">%s</font></td></tr>
    ''' % (bgcol, fgcol, title)
        if prelude:
            result = result + '''
<tr bgcolor="%s"><td rowspan=2>%s</td>
<td colspan=2>%s</td></tr>
<tr><td>%s</td>''' % (bgcol, marginalia, prelude, gap)

Please convert it to simple, validated HTML with the formatting moved to a simple, validated default style sheet.  Liberally apply div/span elements with class/id attributes as necessary.