Revert the last content.js geometry change that caused the viewer to disappear.

Important:
The prior version was better because the viewer was at least visible as a thin scrollable strip. The latest change introduced a regression: now no viewer is shown in the APK.

Instructions:
1. Restore the previous visible-working content.js behavior where the viewer still appeared.
2. Do NOT keep the latest change that converted .tbv-card to position: absolute if that caused the viewer to disappear.
3. Keep the viewer visible, even if still imperfectly laid out.
4. Do not change parsing logic, selectors, colours, stage logic, number grouping, or controls.
5. Do not redesign the UI.
6. Do not replace the overlay with native Android UI.

Then, make only this separate wrapper-level correction:
- In WebView settings, set:
  useWideViewPort = false
  loadWithOverviewMode = false

Reason:
We need to return to the last known visible state first, then test whether WebView overview scaling is what is compressing the visible panel into a bottom strip.

Output:
- full corrected MainActivity.kt
- full corrected content.js
- no redesign
- no extra refactoring