PR #440 restored natural table width and horizontal scrolling for the
default GitHub-2020 theme (via its own `body table` rule) and removed the
column-collapsing `word-break: break-word` from export.css for all themes.

The other ten themes, however, declare bare `table` rules with no overflow
handling, so a wide table there has no scroll container: it overflows the
pane and relies on document-level scrolling that may not be available.

Add a universal `table` scroll container to export.css (which loads last,
so it applies to every theme except where a higher-specificity `body table`
rule already wins, i.e. the default theme). Use the proven GitHub pattern --
`display: block; width: max-content; max-width: 100%; overflow-x: auto` --
so the scrollbar stays on the table itself.

Scope it to `@media screen` so PDF/print layout remains governed by
print.css; an overflow scroll container would otherwise clip wide tables on
paper rather than scrolling them.

Related to #432

PR #440 restored natural table width and horizontal scrolling for the
default GitHub-2020 theme (via its own `body table` rule) and removed the
column-collapsing `word-break: break-word` from export.css for all themes.

The other ten themes, however, declare bare `table` rules with no overflow
handling, so a wide table there has no scroll container: it overflows the
pane and relies on document-level scrolling that may not be available.

Add a universal `table` scroll container to export.css (which loads last,
so it applies to every theme except where a higher-specificity `body table`
rule already wins, i.e. the default theme). Use the proven GitHub pattern --
`display: block; width: max-content; max-width: 100%; overflow-x: auto` --
so the scrollbar stays on the table itself.

Scope it to `@media screen` so PDF/print layout remains governed by
print.css; an overflow scroll container would otherwise clip wide tables on
paper rather than scrolling them.

Related to #432

)

## Summary

Follow-up to #440. That PR restored natural table width and horizontal
scrolling for the **default GitHub-2020 theme** (via its own `body
table` rule) and removed the column-collapsing `word-break: break-word`
from `export.css` for all themes.

The other ten themes, however, declare bare `table { ... }` rules with
**no overflow handling**, so a wide table under those themes still has
no scroll container — it overflows the pane and relies on document-level
scrolling that may not be available. This PR closes that gap.

## Change

A single rule added to `MacDown/Resources/Extensions/export.css` (which
is appended last in the cascade):

```css
@media screen {
    table {
        display: block;
        width: max-content;
        max-width: 100%;
        overflow-x: auto;
    }
}
```

Design notes:

- **Cascade, not specificity.** The non-default themes use bare `table`
selectors of *equal* specificity; this rule wins because `export.css`
loads last (see `MPRenderer.m`). The default GitHub-2020 theme uses a
higher-specificity `body table` rule and is intentionally left
untouched, keeping #440's behavior.
- **`@media screen` is deliberate.** `export.css` is also present when
the preview is printed to PDF, where WebKit switches to print media. An
unscoped scroll container would *clip* wide tables on paper; the screen
scope confines this to the live preview and browser-viewed HTML and
leaves PDF layout to `print.css` (whose `overflow: visible` reset only
covers `pre`, not tables).
- **`max-width: 100%`** keeps the scrollbar attached to the table itself
rather than relying on document-level horizontal scrolling.

## Testing

Tables are rendered via CSS in the preview WebView, so the existing
fixture tests (which only cover the markdown→HTML step) do not exercise
this behavior. Verify manually on macOS:

1. Open a document containing a wide table (≥10 columns) — the `## Wide
Table` block in `MacDownTests/Fixtures/tables.md` works well.
2. **Default theme (GitHub-2020):** confirm the table keeps its natural
width and scrolls horizontally — i.e. no regression from #440.
3. **Each non-default theme** (Preferences → Rendering → Style): GitHub,
GitHub2, GitHub Tomorrow, Github2 (dark), Google Docs, Gmail, Clearness,
Clearness Dark, Solarized (Light), Solarized (Dark). For each, confirm
the wide table now scrolls horizontally instead of compressing columns.
This is the core thing the PR fixes.
4. **Narrow tables:** confirm small tables still render normally (they
shrink-wrap to content width under this rule, which is expected).
5. **PDF export (regression guard):** with a wide table, File → Export →
PDF under both a default and a non-default theme, and confirm the table
is **not** clipped on the page (the `@media screen` scope should keep
`print.css` in charge).
6. Long-URL cell content still wraps rather than expanding the table
indefinitely (preserved via `overflow-wrap` from #440).

Related to #432

---
_Generated by [Claude
Code](https://claude.ai/code/session_01T1WVepxgPRKafX2wQsz8Fv)_

Co-authored-by: Claude <[email protected]>

Regenerate tables.html golden so the "Wide Table" heading (added in
schuyler#440) carries the slug id emitted by the anchor-id logic, keeping the
exact-match rendering test green against current main.