I think there's a lot still to discover. E.g. recently I found out that it can do this (although getting the table aligned took a couple of refreshes):

   Use pseudographics to render the following HTML:

   <table border="1">
   <tr><th>Name</th><th>Value</th></tr>
   <tr><td rowspan="2">Foo</td><td>123</td></tr>
   <tr><td>456</td></tr>
   <tr><td>Bar</td><td>789</td></tr>
   </table>

   +-------+-------+
   | Name  | Value |
   +-------+-------+
   | Foo   | 123   |
   |       | 456   |
   +-------+-------+
   | Bar   | 789   |
   +-------+-------+

So I guess we could say that GPT-3 also has some kind of simple HTML layout engine! I was particularly impressed that it got rowspan right.

I guess the next step would be to combine HTML with JS and see if GPT-3 has a mutable DOM...