Fix W3C validation: add id to modal title for aria-labelledby

The modal's aria-labelledby="modal-title" now correctly references
the h2 element inside the modal content.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/js/app.js b/js/app.js
index f6dd210..0a563a5 100644
--- a/js/app.js
+++ b/js/app.js
@@ -237,7 +237,7 @@ function openModal(bookId) {
         `}
       </div>
       <div class="modal-details">
-        <h2>${escapeHtml(book.title)}</h2>
+        <h2 id="modal-title">${escapeHtml(book.title)}</h2>
         <p class="author">${escapeHtml(book.author)}</p>
         <div class="modal-meta">
           <div class="meta-item">