HTML emails often use fixed-width tables (e.g. <table width="600">) that
exceed the WebView viewport, causing the right portion of the email to be
clipped with no way to scroll. Fix by injecting CSS that:
- Adds `overflow-x: hidden` to body so wide content does not escape the viewport
- Sets `max-width: 100%` on all elements (via `*`) to scale down wide containers
- Forces `table { width: 100%; }` so fixed-pixel-width email tables reflow to fit
- Adds `td/th { overflow-wrap/word-break }` for wrapping in table cells
- Adds `pre { white-space: pre-wrap; }` so pre-formatted text wraps instead of
stretching the page
Adds a regression test that asserts all four CSS rules are present in the
generated HTML.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
