Summary

Closes #33.

• Makes the subject and sort controls responsive: side by side when there is space, stacked on narrow screens
• Refines the book card so long titles and tags wrap instead of forcing horizontal overflow
• Shows at most five OpenLibrary subject tags and adds a +N more indicator for the remainder
• Keeps the existing book navigation and favorites behaviour unchanged

Implementation

• src/App.tsx: groups the subject and sort controls in a shared responsive layout container
• src/App.css: adds the two-column desktop layout, narrow-screen spacing, and mobile heading sizing
• src/components/BookCard.tsx: derives the five visible subjects and remaining-subject count from the book data
• src/components/BookCard.css: improves grid sizing, long-text wrapping, subject-tag layout, and the narrow-screen cover ratio
• src/components/BookCard.test.tsx: tests that a long list is limited and reports the hidden count
• src/__snapshots__/App.test.tsx.snap and src/components/__snapshots__/BookCard.test.tsx.snap: deliberately updated for the new layout wrapper and accessible subject-list name

User flow

1. On a larger screen, subject and sorting choices are presented together without taking unnecessary vertical space.
2. On a narrow screen, the choices stack and remain full-width and readable.
3. A book with many OpenLibrary subjects displays its first five tags plus a clear count such as +7 more.
4. Long titles and tags wrap inside the card rather than expanding the page horizontally.
5. Adding a favorite still immediately changes the button state and keeps the book in the Favorites overview.

Validation

• npm run format:check
• npm run lint
• npm test — 52 tests passed across 12 test files
• npm run build

Checklist

• Scope is limited to feat: make the library view responsive and limit long subject lists #33
• Existing interactions remain covered by tests
• Snapshots were reviewed and updated deliberately
• No UI library or inline static styling added
• Reviewer: check the layout at a 320 px-wide viewport before merge