Update extra.css

Author: blueshank-gh

docs/stylesheets/extra.css

@@ -59,7 +59,7 @@
   width: 100%;
   margin: 0.5rem 0;
   height: 1.2rem;
-  background-color: #070b10;
+  background-color: #0A0A0A;
   position: relative;
 }