fix(styling): fixed white background for markdown block codes

rhodecode/public/css/legacy_code_styles.less

@@ -287,7 +287,7 b' div.markdown-block #message {'
     font-family: @text-monospace;
     font-size: 11px;
     .border-radius(@border-radius);
-    background-color: white;
+    background-color: transparent;
     color: @grey3;
 }