Use design tokens for share-panel background/border/padding and 10px element gap

src/features/online-board/components/BoardDetailsHeader/BoardDetailsHeader.scss

@@ -141,10 +141,10 @@
     position: absolute;
     top: 100%;
     right: 0;
-    background: #fff;
+    background: colors.$white;
     border: 1px solid colors.$border-blue;
-    border-radius: 3px;
-    padding: 20px;
+    border-radius: vars.$border-radius;
+    padding: vars.$space-xl;
     box-shadow: 0 2px 2px rgba(177, 177, 177, 0.15);
     z-index: 10;
   }
@@ -154,7 +154,9 @@
     align-items: flex-start;
 
     > div + div {
-      margin-left: 16px;
+      // Angular sets $space-m (10px) between share icons; previous 16px
+      // misaligned the tile stack against the page-level overlay panel.
+      margin-left: vars.$space-m;
     }
 
     .share-element {