Fix Talawa title colour bug (#3095)

Co-authored-by: Abhi-MS <[email protected]>

Author: Abhi-MS

docs/src/css/index.css

@@ -39,7 +39,7 @@
 
 /* Navbar */
 .navbar__brand {
-  color: var(--brand);
+  color: var(--brand-color);
   font-size: 20px;
 }