feat: responsive grid with scrollable area and fixed hint column

- Add CSS variables (--cell, --cell-font, --trigger-h) for responsive cell sizing
- Shrink grid cells at 600px and 420px breakpoints
- Add .page-body wrapper with 16px horizontal padding to prevent edge collisions
- Separate hint column from scrollable grid: hints rendered outside the table in a fixed flex column, only the letter grid scrolls horizontally

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

assets/styles/app.css

@@ -21,6 +21,9 @@
     --radius-sm:       6px;
     --radius-md:       10px;
     --radius-lg:       18px;
+    --cell:            38px;
+    --cell-font:       15px;
+    --trigger-h:       28px;
 }
 
 body {
@@ -31,6 +34,11 @@ body {
     margin: 0;
 }
 
+.page-body {
+    padding: 0 16px;
+    box-sizing: border-box;
+}
+
 /* ── Game grid ── */
 
 #actors {
@@ -40,22 +48,19 @@ body {
 }
 
 #actors td {
-    width: 38px;
-    height: 38px;
+    width: var(--cell);
+    height: var(--cell);
     text-align: center;
     vertical-align: middle;
 }
 
-#actors td:first-child {
-    padding-right: 12px;
-}
 
 .letter-input {
-    width: 38px;
-    height: 38px;
+    width: var(--cell);
+    height: var(--cell);
     text-align: center;
     font-family: 'Inter', sans-serif;
-    font-size: 15px;
+    font-size: var(--cell-font);
     font-weight: 700;
     border: 2px solid var(--border);
     border-radius: var(--radius-sm);
@@ -80,11 +85,11 @@ body {
 }
 
 .letter-static {
-    width: 38px;
-    height: 38px;
+    width: var(--cell);
+    height: var(--cell);
     text-align: center;
     font-family: 'Inter', sans-serif;
-    font-size: 15px;
+    font-size: var(--cell-font);
     font-weight: 700;
     text-transform: uppercase;
     color: var(--text);
@@ -103,11 +108,11 @@ body {
 /* ── Popover ── */
 
 .popover-trigger {
-    width: 38px;
-    height: 28px;
+    width: var(--cell);
+    height: var(--trigger-h);
     border-radius: 6px;
     border: none;
-    background: #F02287;
+    background: var(--orange);
     cursor: pointer;
     font-size: 14px;
     font-weight: 600;
@@ -120,7 +125,7 @@ body {
 }
 
 .popover-trigger:hover {
-    background: #d41a76;
+    background: var(--orange-mid);
 }
 
 .actor-popover {
@@ -515,7 +520,8 @@ body {
 /* ── Game card ── */
 
 .game-container {
-    max-width: fit-content;
+    width: fit-content;
+    max-width: 100%;
     margin: 56px auto;
     padding: 24px 32px 32px;
     background: var(--surface);
@@ -525,7 +531,36 @@ body {
 }
 
 .game-container #actors {
-    margin: 16px auto 0;
+    margin: 0;
+}
+
+.game-grid-area {
+    display: flex;
+    align-items: flex-start;
+    margin-top: 16px;
+}
+
+.hint-col {
+    display: flex;
+    flex-direction: column;
+    padding-top: 5px;
+    gap: 5px;
+    flex-shrink: 0;
+    padding-right: 12px;
+}
+
+.hint-cell {
+    height: var(--cell);
+    display: flex;
+    align-items: center;
+}
+
+.hint-separator {
+    height: 12px;
+}
+
+.game-grid-scroll {
+    overflow-x: auto;
 }
 
 /* ── Game actions ── */
@@ -592,3 +627,29 @@ body {
     color: var(--orange);
     background: var(--surface-tint);
 }
+
+/* ── Responsive grid ── */
+
+@media (max-width: 600px) {
+    :root {
+        --cell:       30px;
+        --cell-font:  12px;
+        --trigger-h:  22px;
+    }
+
+    .game-container {
+        padding: 16px 16px 24px;
+    }
+}
+
+@media (max-width: 420px) {
+    :root {
+        --cell:       24px;
+        --cell-font:  10px;
+        --trigger-h:  18px;
+    }
+
+    #actors {
+        border-spacing: 3px;
+    }
+}