fix(hub): remove Primer border-top and box-shadow between individual nav items

Author: Phatfella

public/styles/global.css

@@ -158,20 +158,25 @@ svg {
 }
 
 /* -- Nav links --------------------------------------------- */
-/* .SideNav-item (Primer) + .nav-link (ours) + optional .active */
+/* Strip ALL Primer SideNav-item borders — separators between
+   individual pages are unwanted; only section borders are used. */
+.SideNav-item.nav-link,
+.SideNav-item.nav-link:first-child,
+.SideNav-item.nav-link:last-child {
+  border-top: none !important;
+  box-shadow: none !important;
+}
+
 .SideNav-item.nav-link {
   display: block;
   padding: 5px 16px 5px 14px;
   font-size: 0.875rem;
   font-weight: 400;
   color: var(--fgColor-default, var(--color-fg-default));
-  border: none;
   border-left: 2px solid transparent;
   background: transparent;
   text-decoration: none;
   line-height: 1.5;
-  border-top: none;
-  /* override Primer SideNav separator */
 }
 
 .SideNav-item.nav-link:hover {