style: add bottom margin to navbar

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

rcon.css

@@ -110,6 +110,9 @@ a:hover { color: #fff; text-decoration: none; }
 }
 
 /* Navbar text color override */
+#server-header {
+  margin-bottom: 1rem;
+}
 .navbar-dark .navbar-text {
   color: rgba(255, 255, 255, 0.85);
 }