Fix Winners by Category borders: dark between categories, light within

- Light border (1px #eee) between score and model name within same category
- Dark border (2px #999) between different categories

Co-authored-by: openhands <openhands@all-hands.dev>

content.py

@@ -1071,10 +1071,12 @@ h3 .header-link-icon {
     color: var(--color-primary-dark);
     padding-left: 12px;
     min-width: 50px;
+    border-right: 1px solid #eee;
 }
 
 .dark .winners-unified-table .score-cell {
     color: var(--color-primary-accent);
+    border-right-color: var(--color-neutral-700);
 }
 
 .winners-unified-table .model-cell {
@@ -1082,12 +1084,12 @@ h3 .header-link-icon {
     color: var(--color-text-dark);
     font-weight: 500;
     padding-right: 12px;
-    border-right: 1px solid #eee;
+    border-right: 2px solid #999;
 }
 
 .dark .winners-unified-table .model-cell {
     color: #fff;
-    border-right-color: var(--color-neutral-700);
+    border-right-color: var(--color-neutral-500);
 }
 
 .winners-unified-table td:nth-last-child(1) {