Revert category borders to #999 (medium grey)

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

content.py

@@ -1022,14 +1022,14 @@ h3 .header-link-icon {
     font-size: 13px;
     color: var(--color-text-dark);
     border-bottom: 2px solid var(--color-primary-accent) !important;
-    border-right: 2px solid #333 !important;
+    border-right: 2px solid #999 !important;
     white-space: nowrap;
 }
 
 .dark .winners-unified-table .category-header {
     color: #fff;
     border-bottom-color: var(--color-primary-accent) !important;
-    border-right-color: var(--color-neutral-300) !important;
+    border-right-color: var(--color-neutral-500) !important;
 }
 
 .winners-unified-table .category-header:last-child {
@@ -1084,12 +1084,12 @@ h3 .header-link-icon {
     color: var(--color-text-dark);
     font-weight: 500;
     padding-right: 12px;
-    border-right: 2px solid #333;
+    border-right: 2px solid #999;
 }
 
 .dark .winners-unified-table .model-cell {
     color: #fff;
-    border-right-color: var(--color-neutral-300);
+    border-right-color: var(--color-neutral-500);
 }
 
 .winners-unified-table td:nth-last-child(1) {