bug: fix replacement for param writer_name -> writer correctly. Use the html4css1 writer for now. If you use the html5_polyglot you end up with: <main> processed rst </main> rather than (html4css1 writer's): <div class="document"> processed rst </div> there can only be one <main> per document. Each message must not be inside a <main> tag. I could string munge the main tag to a div. But that's ugly. The correct way is to subclass html5_polyglot and override the HTMLTrnslator::documenttag_args replacing {'tagname': 'main'} with {'tagname': 'div', "CLASS": "document"} or something similar. That's a change for another time.

<tal:block metal:use-macro="templates/page/macros/icing">
<title metal:fill-slot="head_title"
 i18n:translate="">Registration in progress - <span i18n:name="tracker"
 tal:replace="config/TRACKER_NAME" /></title>
<span metal:fill-slot="body_title" tal:omit-tag="python:1"
 i18n:translate="">Registration in progress...</span>
<td class="content" metal:fill-slot="content">

<p i18n:translate="">You will shortly receive an email
to confirm your registration. To complete the registration process,
visit the link indicated in the email.
</p>

</td>
</tal:block>