HTML tables should have borders

[Axel-Naumann]

This table:

+------------+------------------------------------------------------+------------------------------------------------+
| Category   | *reflexpr-operand*                                   | `reflect` Concept                              |
+============+======================================================+================================================+
| Type       | *class-name* designating a union                     | `reflect::Record`                              |
+------------+------------------------------------------------------+------------------------------------------------+
|            | *class-name* designating a closure type              | `reflect::Lambda`                              |
+------------+------------------------------------------------------+------------------------------------------------+

is rendered without cell borders when generating HTML. It would be nice if tables would have cell borders in HTML, just like they have for the C++ standard PDF. This would make complex cells much more readable. (I notice in the reflection TS; CWG will surely appreciate an improvement there!)

[mpark]

Closed by 546c89b.

The above table now generates: