diff --git a/web/src/app.css b/web/src/app.css
index 4b0182e..4d4c1ab 100644
--- a/web/src/app.css
+++ b/web/src/app.css
@@ -33,8 +33,8 @@ body {
   gap: 0;
 }
 
-/* Decorative cross-hatch divider between mini-cards on the player sheet,
-   echoing the ✚✚✚ blue borders on a Tân Tân BAMBOORAFT card. */
+/* Decorative cross-hatch borders that frame and segment the player
+   sheet, echoing the ✚✚✚ blue borders on a Tân Tân BAMBOORAFT card. */
 .section-divider {
   height: 8px;
   background-image: repeating-linear-gradient(
@@ -45,8 +45,19 @@ body {
   );
   background-color: rgb(227 242 253 / 0.7);
 }
+.section-divider-vertical {
+  width: 8px;
+  background-image: repeating-linear-gradient(
+    0deg,
+    transparent 0 6px,
+    #1e88e5 6px 8px,
+    transparent 8px 14px
+  );
+  background-color: rgb(227 242 253 / 0.7);
+}
 @media (prefers-color-scheme: dark) {
-  .section-divider {
+  .section-divider,
+  .section-divider-vertical {
     background-color: rgb(13 71 161 / 0.4);
   }
 }
diff --git a/web/src/lib/PlayerBoard.svelte b/web/src/lib/PlayerBoard.svelte
index 93b235d..c03f8ad 100644
--- a/web/src/lib/PlayerBoard.svelte
+++ b/web/src/lib/PlayerBoard.svelte
@@ -162,50 +162,61 @@
   <div class="relative">
     <div
       aria-label="Bảng lô tô"
-      class="rounded-2xl overflow-hidden shadow-xl shadow-slate-200/50 dark:shadow-black/30 border border-slate-200 dark:border-slate-700"
+      class="rounded-md overflow-hidden shadow-xl shadow-slate-200/50 dark:shadow-black/30"
     >
-      {#each SECTIONS as startRow, sectionIdx (sectionIdx)}
-        {#if sectionIdx > 0}
-          <div class="section-divider" aria-hidden="true"></div>
-        {/if}
-        <div class="section-label">{SECTION_LABELS[sectionIdx]}</div>
-        <div class="loto-grid">
-          {#each grid.slice(startRow, startRow + 3).flat() as num, idx (idx)}
-            {@const row = startRow + Math.floor(idx / 9)}
-            {@const col = idx % 9}
-            {@const hasNumber = num > 0}
-            {@const isCrossed = hasNumber && !!crossed[row]?.[col]}
-            {@const rowComplete = hasNumber && rowCompleteness[row]}
-
-            {#if !hasNumber}
-              <div
-                aria-hidden="true"
-                class="relative aspect-[3/5] border-r border-b border-slate-300/60 dark:border-slate-700/60"
-                style:background-color="var(--empty-cell-bg)"
-              ></div>
-            {:else}
-              <button
-                type="button"
-                aria-label="Số {num}{isCrossed ? ', đã đánh dấu' : ''}"
-                aria-pressed={isCrossed}
-                onclick={() => handleCellClick(row, col)}
-                class="tan-tan-num relative flex items-center justify-center
-                       aspect-[3/5] text-2xl sm:text-3xl
-                       border-r border-b border-slate-300/60 dark:border-slate-700/60
-                       transition-all select-none cursor-pointer
-                       focus:outline-none focus:ring-2 focus:ring-inset focus:ring-indigo-400
-                       {isCrossed
-                         ? rowComplete
-                           ? 'cell-crossed bg-emerald-100 dark:bg-emerald-900/40 text-emerald-600 dark:text-emerald-400'
-                           : 'cell-crossed bg-red-50 dark:bg-red-950/30 text-red-500 dark:text-red-500'
-                         : 'bg-white dark:bg-slate-800 text-black dark:text-slate-100 hover:bg-indigo-50 dark:hover:bg-indigo-950/30 hover:text-indigo-600 dark:hover:text-indigo-400'}"
-              >
-                {num}
-              </button>
+      <!-- Top frame -->
+      <div class="section-divider" aria-hidden="true"></div>
+      <div class="flex">
+        <!-- Left frame -->
+        <div class="section-divider-vertical" aria-hidden="true"></div>
+        <div class="flex-1">
+          {#each SECTIONS as startRow, sectionIdx (sectionIdx)}
+            {#if sectionIdx > 0}
+              <div class="section-divider" aria-hidden="true"></div>
             {/if}
+            <div class="section-label">{SECTION_LABELS[sectionIdx]}</div>
+            <div class="loto-grid">
+              {#each grid.slice(startRow, startRow + 3).flat() as num, idx (idx)}
+                {@const row = startRow + Math.floor(idx / 9)}
+                {@const col = idx % 9}
+                {@const hasNumber = num > 0}
+                {@const isCrossed = hasNumber && !!crossed[row]?.[col]}
+                {@const rowComplete = hasNumber && rowCompleteness[row]}
+
+                {#if !hasNumber}
+                  <div
+                    aria-hidden="true"
+                    class="relative aspect-[3/5]"
+                    style:background-color="var(--empty-cell-bg)"
+                  ></div>
+                {:else}
+                  <button
+                    type="button"
+                    aria-label="Số {num}{isCrossed ? ', đã đánh dấu' : ''}"
+                    aria-pressed={isCrossed}
+                    onclick={() => handleCellClick(row, col)}
+                    class="tan-tan-num relative flex items-center justify-center
+                           aspect-[3/5] text-2xl sm:text-3xl
+                           transition-all select-none cursor-pointer
+                           focus:outline-none focus:ring-2 focus:ring-inset focus:ring-indigo-400
+                           {isCrossed
+                             ? rowComplete
+                               ? 'cell-crossed bg-emerald-100 dark:bg-emerald-900/40 text-emerald-600 dark:text-emerald-400'
+                               : 'cell-crossed bg-red-50 dark:bg-red-950/30 text-red-500 dark:text-red-500'
+                             : 'bg-white dark:bg-slate-800 text-black dark:text-slate-100 hover:bg-indigo-50 dark:hover:bg-indigo-950/30 hover:text-indigo-600 dark:hover:text-indigo-400'}"
+                  >
+                    {num}
+                  </button>
+                {/if}
+              {/each}
+            </div>
           {/each}
         </div>
-      {/each}
+        <!-- Right frame -->
+        <div class="section-divider-vertical" aria-hidden="true"></div>
+      </div>
+      <!-- Bottom frame -->
+      <div class="section-divider" aria-hidden="true"></div>
     </div>
 
     {#if toast}