Share modal: a hidden modal must not cover the board (.modal[hidden] display none)

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

public/style.css

@@ -61,6 +61,7 @@ textarea{width:100%;padding:12px 14px;border-radius:12px;border:1px solid var(--
 .badge-a:hover{border-color:var(--edge-hi);transform:translateY(-2px)} .badge-a img{width:100%;aspect-ratio:1;object-fit:cover;border-radius:12px;display:block}
 .badge-a .bl{font-weight:800;margin-top:10px;font-size:14px} .badge-a .bs{font-size:12px;color:var(--muted);margin:4px 0 8px}
 .badge-a.locked img{filter:grayscale(1) brightness(.4)} .badge-a.locked .bl{color:var(--dim)}
+.modal[hidden]{display:none}
 .modal{position:fixed;inset:0;z-index:1000;background:rgba(8,6,20,.82);backdrop-filter:blur(8px);display:flex;align-items:center;justify-content:center;padding:20px;overflow:auto}
 .modal-card{position:relative;width:100%;max-width:520px;background:linear-gradient(180deg,#171036,#0e0a22);border:1px solid var(--edge-hi);border-radius:22px;padding:22px;box-shadow:0 30px 90px rgba(0,0,0,.6)}
 .modal-x{position:absolute;right:12px;top:10px;width:36px;height:36px;border-radius:50%;border:1px solid var(--edge);background:var(--glass);color:var(--ink);font-size:22px;cursor:pointer}