fix: backgammon board larger — 820px default, 900px on large screens

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

public/css/backgammon.css

@@ -27,9 +27,9 @@
     gap: 16px;
     justify-content: center;
     align-items: flex-start;
-    max-width: 1200px;
+    max-width: 1300px;
     margin: 0 auto;
-    padding: 8px 16px;
+    padding: 4px 8px;
     direction: ltr;
 }
 
@@ -47,8 +47,8 @@
 .bg-board {
     position: relative;
     width: 100%;
-    max-width: calc(100vw - 340px);
-    aspect-ratio: 1.4 / 1;
+    max-width: 820px;
+    aspect-ratio: 1.35 / 1;
     background: var(--bg-board-wood);
     border-width: 10px;
     border-style: solid;
@@ -575,8 +575,8 @@
 .bg-side-panel {
     display: flex;
     flex-direction: column;
-    gap: 12px;
-    width: 240px;
+    gap: 10px;
+    width: 200px;
     flex-shrink: 0;
     background: var(--bg-2, rgba(0,0,0,0.2));
     border-radius: 12px;
@@ -997,7 +997,7 @@
 /* ─── Responsive: Large screens ──────────────────────────────────────────── */
 @media (min-width: 1024px) {
     .bg-board {
-        max-width: calc(100vw - 360px);
+        max-width: 900px;
     }
 
     :root {