Q:

Cant fine id tag in wordpress

I want to change some div background color in my word press web site , I can find css id in inspect element and  change the color but i can't find css id in css style sheet . 
http://pajohantest.ir/ is my web site and i want to change the upper black area color.
+
when i change this tag background color : 
inspect element 
  media="all"
  #masthead, #homepage-message, #footer-sidebar, article .entry-format, blockquote, pre {
    background-color: #111;
  } 

and this is the masthead tag in scc style sheet and there is no background option to change 
#masthead .breadcrumb {
  padding-top: 25px;
  padding-top: 2.5rem;

A:

The background-color property is set in Line 40 of you dark.css File. Its set for the  <header id="masthead" role="banner"> Tag ) 

