Remove useless css code

Author: Wilfried OLLIVIER

html/templates/styles.css

@@ -92,11 +92,3 @@ h6 {
   overflow-x: scroll;
   overflow-y: hidden;
 }
-
-.stdout-prefix {
-  color: #900603;
-}
-
-.stderr-prefix {
-  color: #028a0f;
-}