## Summary

- Add subtle background card with left accent border to method headers,
visually separating the API signature zone from documentation prose
- New `--color-sig-bg` design token (lighter than `--color-code-bg`) for
both light and dark themes
- Source button repositioned with absolute positioning (was float-based)
- Method heading links no longer inherit global underline styles
- Description body gets slight left padding to align with the accent
border

CSS-only change — no template modifications.

## Before / After

| Before | After |
|--------|-------|
| <img width="819" height="1311" alt="sig-card-before"
src="https://github.com/user-attachments/assets/729fbc57-a287-46b3-a511-ab757884c9ef"
/> | <img width="810" height="1265" alt="Screenshot 2026-04-02 at 15 25
10"
src="https://github.com/user-attachments/assets/1db4d11f-314f-4ced-ab81-b694543a7c22"
/> |